Home › GK Questions Asked › Chemistry › Metals and Non-metals

Metals and Non-metals PYQs – Chemistry, SSC & Railway

153 Metals and Non-metals (Chemistry) questions asked in recent SSC and Railway exams, newest first, with exam, date & shift, answers and solutions.

📚 153 questionsSSC 6 · Railway 147
12
SSC Stenographer 2026 – 10 September 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q1. Why is stainless steel preferred for kitchen use over iron?

  1. (a) It is lighter
  2. (b) It retains heat better
  3. (c) It resists corrosion
  4. (d) It contains calcium
Answer & solution

Answer: (c) It resists corrosion

Answer: Option 3 — It resists corrosion
Stainless steel is an alloy of iron with chromium, and the chromium forms a thin, invisible chromium oxide layer that seals the surface.
Plain iron has no such layer, so in moist kitchen air it rusts.
Revision note — Corrosion, rusting and alloys
• Rust is hydrated iron(III) oxide, Fe₂O₃·xH₂O. Iron rusts only when both oxygen and water are present — not in dry air, and not in boiled water sealed under oil.
• Stainless steel contains iron, carbon and at least about 10.5 per cent chromium, usually with nickel; the chromium oxide film re-forms itself whenever the surface is scratched.
• Galvanisation coats iron with zinc. Zinc is more reactive, so it corrodes first and protects the iron even where the coating is broken — sacrificial protection.
• Other ways to stop corrosion are painting, oiling and greasing, chrome plating, anodising and alloying, all of which keep out air and moisture.
• Common alloys: brass = copper + zinc; bronze = copper + tin; steel = iron + carbon; solder = tin + lead.
• Copper turns green in moist air (basic copper carbonate) and silver goes black (silver sulphide) — corrosion is not confined to iron.
Do not mix these up
• Corrosion resistance vs lightness — stainless steel is about as dense as iron, roughly 7.9 g/cm³; it is not the lighter metal. That role belongs to aluminium.
• Stainless steel vs galvanised iron — stainless steel resists rust because of chromium inside the alloy; galvanised iron is ordinary iron with a zinc coating on top.
Also asked from this topic: the reddish-brown coating on iron (hydrated iron(III) oxide); the method that protects by sacrificing a metal (galvanisation); when iron rusts (moist air, oxygenated water).
RRB Group D 2025-26 – 25 August 2026 Shift 1 · Physical properties of metals and non-metals

Q2. Consider the following statements about non-metals and select the correct option.Statement I: A solid substance that is dull, brittle, and does not conduct electricity in the solid state is most likely a non-metal.Statement II: All non-metals are dull, brittle solids and do not conduct electricity in the solid state.

  1. (a) Both statements are correct
  2. (b) Both statements are incorrect
  3. (c) Statement I is incorrect, but Statement II is correct
  4. (d) Statement I is correct, but Statement II is incorrect
Answer & solution

Answer: (d) Statement I is correct, but Statement II is incorrect

Correct Answer:
Correct Answer: Option 4 – Statement I is correct, but Statement II is incorrect
Explanation:
Statement Iis correct: dull, brittle, non-conducting solids are typically non-metals — this is a valid general indicator.Statement IIis incorrect because it is an absolute (over)generalization: there are exceptions among non-metals — e.g.,iodineis lustrous (shiny),graphite(a form of carbon, a non-metal) conducts electricity, and some non-metals (like bromine) are liquid, not solid, at room temperature.
Important Facts:
• Graphite is a well-known exception: a non-metal that conducts electricity due to delocalized electrons.
• Iodine is a non-metal that has a metallic lustre.
• Non-metals exist in all three states of matter — solid, liquid (bromine), and gas.
RRB Group D 2025-26 – 25 August 2026 Shift 2 · Metallurgy - extraction and refining

Q3. Which substance is commonly used as a reducing agent to extract metals like zinc from their oxides?

  1. (a) Sulfur
  2. (b) Nitrogen
  3. (c) Oxygen
  4. (d) Carbon
Answer & solution

Answer: (d) Carbon

Correct Answer:
Correct Answer: Option 4 – Carbon
Explanation:
Carbon (in the form of coke)is commonly used as a reducing agent in metallurgy to extract metals like zinc from their oxides. For example: ZnO + C → Zn + CO. Carbon removes oxygen from the metal oxide, reducing it to the free metal.
RRB Group D 2025-26 – 25 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q4. What is the main reason silver articles turn black when exposed to air for a long period?

  1. (a) Formation of a silver sulphide coating
  2. (b) Accumulation of dust particles on the surface
  3. (c) Formation of silver chloride by reaction with chlorine in the air
  4. (d) Formation of silver oxide by reaction with oxygen
Answer & solution

Answer: (a) Formation of a silver sulphide coating

Correct Answer:
Correct Answer: Option 1 – Formation of a silver sulphide coating
Explanation:
Silver articles turn black on prolonged exposure to air because silver reacts slowly with trace amounts ofhydrogen sulphide (H₂S)gas present in the air (from pollution, organic matter decay, etc.), forming a thin black coating ofsilver sulphide (Ag₂S)on the surface. This is a classic example of tarnishing due to a chemical reaction.
RRB Group D 2025-26 – 25 August 2026 Shift 3 · Metallurgy - extraction and refining

Q5. Which method is commonly used to extract sodium from its compound?

  1. (a) Distillation
  2. (b) Thermal decomposition
  3. (c) Electrolytic reduction
  4. (d) Heating with carbon
Answer & solution

Answer: (c) Electrolytic reduction

Correct Answer:
Correct Answer: Option 3 – Electrolytic reduction
Explanation:
Sodium is a highly reactive metal, and reactive metals are extracted via electrolytic reduction of their molten salts. Sodium is obtained by electrolysis of molten sodium chloride (Down's process).
Important Facts:
• Reactivity series metals like Na, K, Ca, Mg, Al are extracted by electrolytic reduction.
• Less reactive metals (e.g., Zn, Fe) are extracted by reduction with carbon.
• Very reactive metals cannot be reduced by carbon or other chemical reducing agents alone.
RRB Group D 2025-26 – 21 August 2026 Shift 1 · Reactivity series

Q6. Given that metal X reacts with CuSO₄ but not with FeSO₄, and metal Y reacts with FeSO₄ but not with ZnSO₄, what is the correct order of decreasing reactivity for Zn, Fe, Cu, X, and Y?

  1. (a) Zn > Y > Fe > X > Cu
  2. (b) Cu > X > Fe > Y > Zn
  3. (c) Fe > X > Zn > Y > Cu
  4. (d) Y > Zn > X > Fe > Cu
Answer & solution

Answer: (a) Zn > Y > Fe > X > Cu

Explanation:
Metal X displaces Cu from CuSO4 (so X is more reactive than Cu) but cannot displace Fe from FeSO4 (so X is less reactive than Fe): Fe > X > Cu.
Metal Y displaces Fe from FeSO4 (so Y is more reactive than Fe) but cannot displace Zn from ZnSO4 (so Y is less reactive than Zn): Zn > Y > Fe.
Combining both chains: Zn > Y > Fe > X > Cu.
Correct Answer: Option 1 – Zn > Y > Fe > X > Cu
RRB Group D 2025-26 – 21 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q7. Anodizing is a process of forming a thick oxide layer of which of the following metals through an electrolytic process?

  1. (a) iron
  2. (b) aluminium
  3. (c) zinc
  4. (d) copper
Answer & solution

Answer: (b) aluminium

Correct Answer:
Correct Answer: Option 2 – aluminium
Explanation:
Anodizing is an electrolytic passivation process used mainly on aluminium, where the metal forms the anode and a thick, durable, corrosion-resistant layer of aluminium oxide is deposited on its surface.
RRB Group D 2025-26 – 21 August 2026 Shift 3 · Ionic compounds and their properties

Q8. Which property is most commonly observed in ionic compounds like sodium chloride?

  1. (a) High electrical conductivity in solid state
  2. (b) Poor electrical conductivity in molten state
  3. (c) High melting and boiling points
  4. (d) Low melting and boiling points
Answer & solution

Answer: (c) High melting and boiling points

Correct Answer:
Correct Answer: Option 3 – High melting and boiling points
Explanation:
Ionic compounds like sodium chloride have strong electrostatic forces of attraction between oppositely charged ions, resulting inhigh melting and boiling points.
Important Facts:
• Ionic compounds conduct electricity in molten/aqueous state (due to free ions) but not in the solid state (ions are fixed in a lattice).
RRB Group D 2025-26 – 20 August 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q9. Anodising is a process used to improve the appearance and durability of aluminium articles. Which of the following statements best explains the principle behind anodising?

  1. (a) Aluminium is dipped in alkali to increase its reactivity.
  2. (b) Aluminium is made the cathode in electrolysis to reduce oxide layer.
  3. (c) Aluminium is made the anode and oxidised to form a thicker protective oxide layer.
  4. (d) Aluminium is coated with zinc to prevent rusting.
Answer & solution

Answer: (c) Aluminium is made the anode and oxidised to form a thicker protective oxide layer.

Correct Answer:
Correct Answer: Option 3 – Aluminium is made the anode and oxidised to form a thicker protective oxide layer.
Explanation:
Anodisingis an electrolytic process in which the aluminium object is made theanode. During electrolysis, the aluminium surface is oxidised, thickening the naturally occurring protective aluminium oxide (Al₂O₃) layer, which improves corrosion resistance and can also be dyed for appearance.
Important Facts:
• Oxidation occurs at the anode (loss of electrons).
• The thickened oxide layer is harder and more corrosion-resistant than the natural film.
• Anodised aluminium is commonly used in utensils, window frames, and consumer goods.
RRB Group D 2025-26 – 20 August 2026 Shift 2 · Ionic compounds and their properties

Q10. What type of bond is formed between a metal and a non-metal?

  1. (a) Metallic bond
  2. (b) Ionic bond
  3. (c) Hydrogen bond
  4. (d) Covalent bond
Answer & solution

Answer: (b) Ionic bond

Correct Answer:
Correct Answer: Option 2 – Ionic bond
Explanation:
A metal (which tends to lose electrons, forming cations) and a non-metal (which tends to gain electrons, forming anions) combine via electrostatic attraction between oppositely charged ions, forming an ionic bond, e.g., NaCl.
Important Facts:
• Metallic bonds occur between atoms of the same metal.
• Covalent bonds typically form between two non-metals.
RRB Group D 2025-26 – 19 August 2026 Shift 1 · Chemical properties of metals

Q11. Which equation correctly represents the reaction between calcium and cold water?

  1. (a) Ca + H₂O → CaH₂ + O₂
  2. (b) Ca + 2H₂O → Ca(OH)₂ + H₂
  3. (c) Ca + H₂O → CaOH₂ + H₂
  4. (d) 2Ca + H₂O → 2CaOH + H₂
Answer & solution

Answer: (b) Ca + 2H₂O → Ca(OH)₂ + H₂

Correct Answer:
Correct Answer: Option 2 – Ca + 2H₂O → Ca(OH)₂ + H₂
Explanation:
Calcium reacts with cold water to form calcium hydroxide and hydrogen gas:Ca + 2H₂O → Ca(OH)₂ + H₂↑. This is a correctly balanced equation (1 Ca, 4 H, 2 O on each side).
Important Facts:
• This reaction is moderately vigorous; the released heat is not enough to ignite the H₂ gas.
• Calcium hydroxide (Ca(OH)₂) is also known as slaked lime.
RRB Group D 2025-26 – 19 August 2026 Shift 2 · Chemical properties of metals

Q12. Aluminium reacts with oxygen. Which chemical formula represents the product of this reaction?

  1. (a) AlO₂
  2. (b) Al₂O
  3. (c) Al₃O₂
  4. (d) Al₂O₃
Answer & solution

Answer: (d) Al₂O₃

Correct Answer:
Correct Answer: Option 4 – Al₂O₃
Explanation:
Aluminium has a valency of +3 and oxygen has a valency of -2. Balancing charges (cross-multiplication of valencies) gives the formulaAl₂O₃(aluminium oxide): 4Al + 3O₂ → 2Al₂O₃.
Important Facts:
• Al₂O₃ is also known as alumina, a key component of bauxite ore and a very stable, protective oxide layer on aluminium metal.
• This protective oxide layer is why aluminium resists corrosion despite being a reactive metal.
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q13. Why does galvanisation protect iron even when the zinc layer is damaged?

  1. (a) Zinc increases iron hardness
  2. (b) Zinc reacts faster with water
  3. (c) Zinc prevents oxygen contact
  4. (d) Zinc corrodes preferentially
Answer & solution

Answer: (d) Zinc corrodes preferentially

Galvanisation and sacrificial protection
Galvanisation coats iron with a layer of zinc. Zinc is more reactive than iron, so even if the zinc coating is scratched or damaged exposing the iron underneath, the zinc continues to corrode (oxidise) preferentially instead of the iron.
This is known assacrificial/cathodic protection— the zinc acts as a sacrificial anode, protecting the iron from rusting even after the coating is damaged.
Correct Answer: Zinc corrodes preferentially
RRB Group D 2025-26 – 18 August 2026 Shift 2 · Metallurgy - extraction and refining

Q14. Which of the following metals is extracted by electrolysis due to its position at the top of the activity series?

  1. (a) Copper
  2. (b) Sodium
  3. (c) Zinc
  4. (d) Iron
Answer & solution

Answer: (b) Sodium

Extraction of Reactive Metals
Metals at the top of the reactivity series (K, Na, Ca, Mg, Al) are highly reactive and cannot be extracted by simple reduction with carbon; they are extracted byelectrolysisof their molten compounds.
Among the given options,Sodiumis the most reactive and top of the activity series, extracted via electrolysis (e.g., of molten NaCl).
Correct Answer: Sodium
RRB Group D 2025-26 – 18 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q15. Why is corrosion considered economically harmful to metallic structures and machinery?

  1. (a) It weakens metals and reduces durability
  2. (b) It improves surface appearance
  3. (c) It enhances metal conductivity
  4. (d) It increases metal reactivity
Answer & solution

Answer: (a) It weakens metals and reduces durability

Economic Impact of Corrosion
Corrosion is the gradual deterioration of metals due to reaction with environmental agents (oxygen, moisture, acids). It eats away the metal surface,weakening structures and reducing their durability and lifespan, leading to costly repairs/replacement of machinery, bridges, pipelines, etc.
Correct Answer: It weakens metals and reduces durability
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Metallurgy - extraction and refining

Q16. Which sequence best describes the steps for obtaining a pure metal from its ore?

  1. (a) Ore is enriched, then metal is extracted, and finally purification is performed.
  2. (b) Ore is purified, then metal is extracted, and finally enrichment is performed.
  3. (c) Ore is melted, then metal is extracted, and finally enrichment is performed.
  4. (d) Metal is extracted, then ore is enriched, and finally purification is performed.
Answer & solution

Answer: (a) Ore is enriched, then metal is extracted, and finally purification is performed.

Concept: Extraction of Metals from Ores
The general sequence for obtaining a pure metal from its ore is:
• 1. Enrichment/concentration of the ore — removing gangue (impurities) to concentrate the ore
• 2. Extraction of the metal — converting the concentrated ore to the metal (via reduction, roasting/calcination followed by reduction, or electrolysis)
• 3. Purification/refining of the metal — obtaining a pure metal, e.g., by electrolytic refining
Correct Answer: Ore is enriched, then metal is extracted, and finally purification is performed.
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Reactivity series

Q17. A student mixes lead metal with iron(II) sulfate solution and observes no visible change. Which statement best explains this observation?

  1. (a) Lead reacts vigorously with iron(II) sulfate forming a new compound.
  2. (b) Lead is less reactive than iron and cannot displace it from its compound.
  3. (c) The reaction is reversible, so no net change is observed.
  4. (d) Lead is more reactive than iron and displaces it from the solution.
Answer & solution

Answer: (b) Lead is less reactive than iron and cannot displace it from its compound.

Concept: Reactivity Series and Displacement Reactions
In the reactivity series of metals, the order (from more to less reactive) around this region is: ... Zn > Fe > Pb > Cu ... Since iron (Fe) is more reactive than lead (Pb), lead cannot displace iron from iron(II) sulfate solution. A more reactive metal is needed to displace a less reactive metal from its salt solution — here it's the reverse, so no reaction (no visible change) occurs.
Correct Answer: Lead is less reactive than iron and cannot displace it from its compound.
RRB Group D 2025-26 – 17 August 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q18. Industrial machines made of steel often operate in moist environments. Which routine maintenance task is most effective in minimizing corrosion and ensuring machine longevity?

  1. (a) Applying lubricating oil on exposed parts
  2. (b) Covering machines with paper sheets
  3. (c) Spraying water on the machines
  4. (d) Wiping machines with dry towels
Answer & solution

Answer: (a) Applying lubricating oil on exposed parts

Preventing Corrosion of Steel Machines
Corrosion (rusting) of steel/iron requires the simultaneous presence of moisture (water) and oxygen. Preventing contact between the metal surface and moist air stops rusting.
Applying lubricating oilon exposed metal parts forms a protective, water-repelling film that keeps out moisture and air, effectively minimizing corrosion — this is a standard, routine maintenance practice for machinery.
Correct Answer: Applying lubricating oil on exposed parts
RRB Group D 2025-26 – 17 August 2026 Shift 2 · Ionic compounds and their properties

Q19. Which of the following pairs of elements is most likely to form an ionic bond?

  1. (a) Nitrogen and oxygen
  2. (b) Magnesium and chlorine
  3. (c) Hydrogen and carbon
  4. (d) Copper and iron
Answer & solution

Answer: (b) Magnesium and chlorine

Formation of Ionic Bonds
Ionic bonds form between a metal (which loses electrons easily, low electronegativity) and a non-metal (which gains electrons easily, high electronegativity), giving a large electronegativity difference.Magnesium (metal) and chlorine (non-metal)readily form the ionic compound MgCl₂.
• Nitrogen and oxygen are both non-metals with similar electronegativities — they form covalent bonds (e.g., NO, NO₂).
• Hydrogen and carbon form covalent bonds (as in hydrocarbons).
• Copper and iron are both metals — they form metallic alloys, not ionic bonds.
Correct Answer: Magnesium and chlorine
RRB Group D 2025-26 – 17 August 2026 Shift 2 · Metallurgy - extraction and refining

Q20. Which of the following statements are correct for electrolytic refining?a. Copper, zinc, and nickel are refined electrolytically.b. In this method, a thin strip of pure metal is used as cathode.c. The insoluble impurities settled at bottom of the anode are known as anode mud.

  1. (a) b and c only
  2. (b) All a, b and c
  3. (c) a and b only
  4. (d) a and c only
Answer & solution

Answer: (b) All a, b and c

Electrolytic Refining
All three statements about electrolytic refining are correct: (a) Metals like copper, zinc and nickel are commonly purified by electrolytic refining. (b) A thin strip/sheet of pure metal is used as the cathode, while the impure metal block is the anode. (c) During refining, insoluble impurities from the impure anode settle at the bottom as a sludge, known asanode mud(anode sludge), which often contains valuable metals like silver and gold.
Correct Answer: All a, b and c
RRB Group D 2025-26 – 17 August 2026 Shift 3 · Chemical properties of metals

Q21. The gas evolved when calcium reacts with water is:

  1. (a) Oxygen
  2. (b) Hydrogen
  3. (c) Nitrogen
  4. (d) Carbon dioxide
Answer & solution

Answer: (b) Hydrogen

Reaction of Calcium with Water
Calcium reacts with cold water (though less vigorously than sodium/potassium):
• Ca + 2H₂O → Ca(OH)₂ + H₂↑
• This produces calcium hydroxide and releaseshydrogen gas, seen as bubbles; the reaction is exothermic but calcium often floats due to the bubbles sticking to it.
Correct Answer: Hydrogen
RRB Group D 2025-26 – 14 August 2026 Shift 2 · Reactivity series

Q22. What primary factor determines whether one element can displace another from its compound?

  1. (a) Difference in solution concentration
  2. (b) Relative reactivity of the elements involved
  3. (c) Difference in atomic masses
  4. (d) Difference in physical state
Answer & solution

Answer: (b) Relative reactivity of the elements involved

Answer: Option 2 – Relative reactivity of the elements involved.
• A more reactive element displaces a less reactive one from its compound;relative reactivitydecides displacement.
RRB Group D 2025-26 – 14 August 2026 Shift 2 · Metallurgy - extraction and refining

Q23. During the electrolytic refining of copper, which of the following correctly matches the components and their roles?
[TABLE]
Component | Role in Refining Process
A. Pure Copper | i. Anode
B. Impure Copper | ii. Cathode
C. Acidified Copper Sulphate | iii. Electrolyte
[/TABLE]

  1. (a) A - iii, B - i, C - ii
  2. (b) A - ii, B - iii, C - i
  3. (c) A - i, B - ii, C - iii
  4. (d) A - ii, B - i, C - iii
Answer & solution

Answer: (d) A - ii, B - i, C - iii

Answer: Option 4 – A - ii, B - i, C - iii.
• In copper's electrolytic refining, the components match the roles as in Option 4 (impure copper anode, pure copper cathode, CuSO₄ electrolyte).
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Chemical properties of metals

Q24. Which of the following statements correctly describes the behaviour of different metals when heated in air?

  1. (a) Potassium and sodium react so vigorously with oxygen that they catch fire
  2. (b) Iron and copper burn with a flame producing metal oxides
  3. (c) Silver and gold burn in air and form thick oxide coatings
  4. (d) All metals burn in air with the same intensity and form metal oxides
Answer & solution

Answer: (a) Potassium and sodium react so vigorously with oxygen that they catch fire

Answer: Option 1 – Potassium and sodium react so vigorously with oxygen that they catch fire.
•K and Naare highly reactive and ignite in air; iron/copper don't burn with a flame, and silver/gold are unreactive.
RRB Group D 2025-26 – 13 August 2026 Shift 1 · Occurrence of metals - ores and minerals

Q25. Metals of medium reactivity are generally found in the form of which compounds?

  1. (a) Oxides, sulphides, or carbonates
  2. (b) Chlorides, silicates, or phosphates
  3. (c) Nitrides, fluorides, or bromides
  4. (d) Peroxides, hydrides, or cyanides
Answer & solution

Answer: (a) Oxides, sulphides, or carbonates

Answer: Option 1 – Oxides, sulphides, or carbonates.
• Moderately reactive metals occur mainly asoxides, sulphides or carbonates.
RRB Group D 2025-26 – 13 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q26. What happens at the anode during anodising?

  1. (a) Carbon dioxide reacts with aluminium to form oxide
  2. (b) Hydrogen gas reacts with aluminium to form oxide
  3. (c) Oxygen gas reacts with aluminium to form oxide
  4. (d) Nitrogen gas reacts with aluminium to form oxide
Answer & solution

Answer: (c) Oxygen gas reacts with aluminium to form oxide

Answer: Option 3 – Oxygen gas reacts with aluminium to form oxide.
• In anodising,oxygen liberated at the anodereacts with aluminium to form a thick protective oxide layer.
RRB Group D 2025-26 – 13 August 2026 Shift 3 · Occurrence of metals - ores and minerals

Q27. Why are few metals NOT found in their native state of nature?

  1. (a) Because they have low melting points.
  2. (b) Because they have high reactivity.
  3. (c) Because they are high density.
  4. (d) Because they are soluble in nature.
Answer & solution

Answer: (b) Because they have high reactivity.

Answer: Option 2 – Because they have high reactivity.
• Highly reactive metals combine readily with other elements, so they arenot found free (native)in nature.
RRB Group D 2025-26 – 12 August 2026 Shift 1 · Reactivity series

Q28. When a metal is placed in the salt solution of another metal and a reaction occurs, what does it indicate about the two metals?

  1. (a) The metal in solution is more reactive
  2. (b) No information about reactivity can be determined
  3. (c) Both metals are equally reactive
  4. (d) The solid metal is more reactive than the metal in solution
Answer & solution

Answer: (d) The solid metal is more reactive than the metal in solution

Answer: Option 4 – The solid metal is more reactive than the metal in solution.
• A displacement reaction occurs when theadded solid metal is more reactiveand displaces the metal from its salt.
RRB Group D 2025-26 – 12 August 2026 Shift 2 · Ionic compounds and their properties

Q29. Which of the following best explains why sodium chloride is solid at room temperature?

  1. (a) It has metallic bonding between atoms.
  2. (b) It forms molecules held by covalent bonds.
  3. (c) It is held together by weak van der Waals forces.
  4. (d) It has a strong electrostatic attraction between ions.
Answer & solution

Answer: (d) It has a strong electrostatic attraction between ions.

Answer: Option 4 – It has a strong electrostatic attraction between ions.
• NaCl is an ionic solid held bystrong electrostatic (ionic) forces, giving a high melting point.
RRB Group D 2025-26 – 11 August 2026 Shift 1 · Ionic compounds and their properties

Q30. Which of the following best explains why ionic compounds are hard but brittle?

  1. (a) Weak attractions make them soft and flexible
  2. (b) They are liquids at room temperature
  3. (c) Strong attractions make them hard; shifting layers break them apart
  4. (d) They have a metallic lattice
Answer & solution

Answer: (c) Strong attractions make them hard; shifting layers break them apart

Answer: Option 3 – Strong attractions make them hard; shifting layers break them apart.
• Strong electrostatic forces make ionic solidshard; but if a layer shifts, like charges align and repel, so the crystal isbrittle.
RRB Group D 2025-26 – 11 August 2026 Shift 2 · Chemical properties of metals

Q31. Which metal forms a protective oxide layer on its surface when heated in air, preventing further oxidation?

  1. (a) Copper
  2. (b) Aluminium
  3. (c) Iron
  4. (d) Sodium
Answer & solution

Answer: (b) Aluminium

Answer: Option 2 – Aluminium.
• Aluminium forms a thin, toughAl₂O₃ (aluminium oxide) layerthat sticks to the surface and prevents further oxidation.
RRB Group D 2025-26 – 11 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q32. Which of the following observations correctly represents corrosion of a metal?

  1. (a) Iron develops reddish-brown surface layer
  2. (b) Aluminium breaks under mechanical load
  3. (c) Silver dissolves completely in water
  4. (d) Copper wire melts when strongly heated
Answer & solution

Answer: (a) Iron develops reddish-brown surface layer

Answer: Option 1 – Iron develops a reddish-brown surface layer.
• Corrosion of iron =rusting, seen as a reddish-brown (hydrated iron oxide) layer.
RRB Group D 2025-26 – 11 August 2026 Shift 3 · Metallurgy - extraction and refining

Q33. Select the option that is true regarding the following two statements labelled Assertion (A) and Reason (R).Assertion (A): Metals such as sodium and potassium are extracted by electrolysis.Reason (R): These metals are highly reactive and cannot be obtained by reduction with carbon.

  1. (a) A is false, but R is true
  2. (b) A is true, but R is false
  3. (c) Both A and R are true, and R is the correct explanation of A
  4. (d) Both A and R are true, but R is not the correct explanation of A
Answer & solution

Answer: (c) Both A and R are true, and R is the correct explanation of A

Answer: Option 3 – Both A and R are true, and R is the correct explanation of A.
• Highly reactive metals (Na, K) can't be reduced by carbon, so they are extracted byelectrolysis– R correctly explains A.
RRB Group D 2025-26 – 10 August 2026 Shift 1 · Metallurgy - extraction and refining

Q34. During the extraction of metals, the sulphide ores are converted into oxides by heating strongly in the presence of excess air. This process is known as:

  1. (a) elimination
  2. (b) calcination
  3. (c) roasting
  4. (d) sulphonation
Answer & solution

Answer: (c) roasting

Answer: Option 3 — roasting
Heating a sulphide ore strongly inexcess airto form the oxide isroasting→ Option 3.
RRB Group D 2025-26 – 10 August 2026 Shift 2 · Physical properties of metals and non-metals

Q35. Which of the following sets correctly represents physical properties commonly exhibited by most metals?

  1. (a) Soft, non-ductile, poor conductor of electricity
  2. (b) Lustrous, malleable, good conductor of electricity
  3. (c) Brittle, non-lustrous, poor conductor of heat
  4. (d) Dull, malleable, non-sonorous
Answer & solution

Answer: (b) Lustrous, malleable, good conductor of electricity

Answer: Option 2 – Lustrous, malleable, good conductor of electricity.
• Most metals arelustrous(shiny),malleable(can be beaten into sheets),ductile(drawn into wires),sonorous, andgood conductorsof heat and electricity.
• Options 1, 3 and 4 list non-metallic properties (soft, brittle, dull, poor conductor), so they are wrong.
RRB Group D 2025-26 – 10 August 2026 Shift 3 · Metallurgy - extraction and refining

Q36. What is used as an anode in the electrolytic refining of nickel?

  1. (a) Nickel acetate
  2. (b) Nickel sulphate
  3. (c) Impure nickel
  4. (d) Nickel carbonate
Answer & solution

Answer: (c) Impure nickel

Answer: Option 3 – Impure nickel.
• In electrolytic refining, theimpure metal (impure nickel)is made theanode, and pure nickel deposits on the cathode.
RRB Group D 2025-26 – 9 August 2026 Shift 1 · Physical properties of metals and non-metals

Q37. Which of the following physical properties is true for metals?

  1. (a) Metals are solid at room temperature
  2. (b) Metals are lustrous and good conductors of electricity
  3. (c) Metals are poor conductors of heat
  4. (d) Metals are brittle and break easily
Answer & solution

Answer: (b) Metals are lustrous and good conductors of electricity

Answer: Option 2 — Metals are lustrous and good conductors of electricity
Metals areshiny (lustrous) and good conductors→ Option 2. (Mercury is liquid; metals are malleable, not brittle.)
RRB Group D 2025-26 – 9 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q38. Which of the following conditions accelerate the corrosion of metals the most?

  1. (a) Pure water and sunlight
  2. (b) Dry air and low temperature
  3. (c) Moist air and presence of salts or acids
  4. (d) Vacuum and darkness
Answer & solution

Answer: (c) Moist air and presence of salts or acids

Answer: Option 3 — Moist air and presence of salts or acids
Corrosion is fastest inmoist air with salts/acids→ Option 3.
RRB Group D 2025-26 – 9 August 2026 Shift 3 · Reactivity series

Q39. Given that: - P displaces Q from its salt solution, - R displaces S from its salt solution, - Q displaces R from its salt solution, - S cannot displace any other metal;Which metal is the most reactive among them?

  1. (a) Q
  2. (b) R
  3. (c) P
  4. (d) S
Answer & solution

Answer: (c) P

Answer: Option 3 — P
P displaces Q, Q displaces R, R displaces S ⟹ reactivity order P > Q > R > S. The most reactive isP→ Option 3.
RRB Group D 2025-26 – 9 August 2026 Shift 3 · Metallurgy - extraction and refining

Q40. Metals low in the reactivity series, such as copper and mercury, are extracted by:

  1. (a) electrolysis of their molten ores
  2. (b) displacement using more reactive metals
  3. (c) reduction with carbon at high temperatures
  4. (d) roasting in air to convert sulphide ores into oxides, followed by heating
Answer & solution

Answer: (d) roasting in air to convert sulphide ores into oxides, followed by heating

Answer: Option 4 — Roasting sulphide ores to oxides, then heating
Low-reactivity metals (Cu, Hg) are extracted byroasting the sulphide to oxide and then heating→ Option 4.
RRB Group D 2025-26 – 6 August 2026 Shift 2 · Reactivity series

Q41. Read the following statements and choose the correct option.Statement I: All metals in the reactivity series can displace hydrogen from dilute acids to form hydrogen gas.Statement II: Metals below hydrogen in the reactivity series do not produce hydrogen gas with dilute acids.

  1. (a) Statement I is true, Statement II is true, and Statement II is the correct explanation of Statement I.
  2. (b) Statement I is true, but Statement II is false.
  3. (c) Statement I is false, but Statement II is true.
  4. (d) Statement I is true, Statement II is true, but Statement II is not the correct explanation of Statement I.
Answer & solution

Answer: (c) Statement I is false, but Statement II is true.

Answer: Option 3 — Statement I false, Statement II true
Metalsbelow hydrogen(Cu, Ag) do NOT displace hydrogen from acids, so I is false; II is true → Option 3.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Metallurgy - extraction and refining

Q42. Which of the following metals is usually extracted from its ore by electrolytic reduction?

  1. (a) Iron
  2. (b) Aluminium
  3. (c) Copper
  4. (d) Zinc
Answer & solution

Answer: (b) Aluminium

Answer: Option 2 — Aluminium
Highly reactive metals likealuminiumare extracted byelectrolytic reduction→ Option 2.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Corrosion and its prevention (galvanisation, etc.)

Q43. Which method effectively prevents corrosion by blocking contact with air and moisture?

  1. (a) Applying paint or protective coating
  2. (b) Heating metal at high temperature
  3. (c) Exposing metal to sunlight
  4. (d) Mixing metal with water
Answer & solution

Answer: (a) Applying paint or protective coating

Answer: Option 1 — Applying paint or protective coating
Paint/coating blocks air and moisture, preventing corrosion → Option 1.
RRB Group D 2025-26 – 5 August 2026 Shift 1 · Chemical properties of metals

Q44. When copper is heated in air, it combines with oxygen to form a black oxide, which is:

  1. (a) copper(III) oxide
  2. (b) copper(I) oxide
  3. (c) copper(II) oxide
  4. (d) copper(IV) oxide
Answer & solution

Answer: (c) copper(II) oxide

Answer: Option 3 — copper(II) oxide
2Cu + O₂ → 2CuO. The black oxide iscopper(II) oxide (CuO)→ Option 3.
RRB Group D 2025-26 – 5 August 2026 Shift 2 · Chemical properties of metals

Q45. When magnesium metal reacts with hot water, what is the main product formed alongside hydrogen gas?

  1. (a) Copper hydroxide
  2. (b) Magnesium oxide
  3. (c) Iron hydroxide
  4. (d) Magnesium hydroxide
Answer & solution

Answer: (d) Magnesium hydroxide

Answer: Option 4 — Magnesium hydroxide
Mg + 2H₂O (hot) →Mg(OH)₂+ H₂↑. The main product with hydrogen ismagnesium hydroxide→ Option 4.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Metallurgy - extraction and refining

Q46. Which of the following statements is CORRECT regarding the refining of metals?

  1. (a) Refining is only used for highly reactive metals.
  2. (b) Refining involves converting the ore to oxide form.
  3. (c) Refining is used to remove impurities from the extracted metal.
  4. (d) Refining is the process of extracting metal from its ore.
Answer & solution

Answer: (c) Refining is used to remove impurities from the extracted metal.

Answer: Option 3 — Refining removes impurities from the extracted metal
Refiningis the final purification step that removes impurities from the extracted metal → Option 3.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Ionic compounds and their properties

Q47. If a metal and a non-metal is mixed to form a compound, which type of charged species is most likely present, and how are they classified?

  1. (a) Ions; classified as cations and anions
  2. (b) Atoms; classified as protons and neutrons
  3. (c) Elements; classified as metals and non-metals
  4. (d) Molecules; classified as acids and bases
Answer & solution

Answer: (a) Ions; classified as cations and anions

Answer: Option 1 — Ions; cations and anions
A metal + non-metal forms anionic compoundwithcations and anions→ Option 1.
RRB Group D 2025-26 – 4 August 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q48. Which of the following methods prevents corrosion by sacrificing another metal?

  1. (a) Galvanisation
  2. (b) Anodising
  3. (c) Painting
  4. (d) Alloying
Answer & solution

Answer: (a) Galvanisation

Answer: Option 1 — Galvanisation
Galvanisationcoats iron withzinc, a more reactive metal that corrodes in preference (sacrificial protection) → Option 1.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Important metals and their facts

Q49. Which of the following is the purest form of iron?

  1. (a) Hard steel
  2. (b) Limonite
  3. (c) Wrought iron
  4. (d) Stainless steel
Answer & solution

Answer: (c) Wrought iron

Answer: Option 3 — Wrought iron
Wrought ironis the purest form of iron (about 99.5% iron, very low carbon) → Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 1 · Occurrence of metals - ores and minerals

Q50. A mineralogist discovers a new metallic ore in the earth's crust. If the ore is primarily a sulphide, the metal is most likely to belong to the:

  1. (a) Top of the activity series
  2. (b) Middle of the activity series
  3. (c) Noble gases, which do not form ores
  4. (d) Bottom of the activity series
Answer & solution

Answer: (b) Middle of the activity series

Answer: Option 2 — Middle of the activity series
Concept:Moderately reactive metals (Zn, Fe, Pb, Cu — themiddleof the activity series) commonly occur assulphide(and oxide/carbonate) ores. Highly reactive metals occur as chlorides/oxides; least reactive occur free. Since the ore is a sulphide, the metal lies in the middle → Option 2.
RRB Group D 2025-26 – 3 August 2026 Shift 2 · Corrosion and its prevention (galvanisation, etc.)

Q51. A shiny iron nail was left in four different conditions for several days.I. Dry air in a sealed containerII. Water containing dissolved oxygenIII. Water that had been boiled and then covered with oilIV. Moist airIn which of the above conditions will rusting of iron most likely occur?

  1. (a) I and III only
  2. (b) I, II and IV
  3. (c) II and IV only
  4. (d) II, III and IV
Answer & solution

Answer: (c) II and IV only

Answer: Option 3 — II and IV only
Rusting needsboth water/moisture and oxygen.
I (dry air) – no water ✗; III (boiled water + oil cover) – oxygen removed ✗; II (water with dissolved O₂) ✓; IV (moist air) ✓. SoII and IV→ Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 2 · Physical properties of metals and non-metals

Q52. Which statement best describes the electrical conductivity of non-metals in their pure form?

  1. (a) Non-metals do not conduct electricity
  2. (b) Non-metals have high electrical conductivity
  3. (c) Non-metals conduct electricity as metals do
  4. (d) Non-metals conduct electricity efficiently
Answer & solution

Answer: (a) Non-metals do not conduct electricity

Answer: Option 1 — Non-metals do not conduct electricity
Most non-metals arepoor conductors (insulators)in their pure form (exception: graphite). So generally theydo not conduct electricity→ Option 1.
RRB Group D 2025-26 – 3 August 2026 Shift 3 · Metallurgy - extraction and refining

Q53. Which process is commonly used to extract iron, a metal in the middle of the activity series, from its ore?

  1. (a) Reduction with carbon (coke)
  2. (b) Electrolytic reduction
  3. (c) Reduction with hydrogen
  4. (d) Thermal decomposition
Answer & solution

Answer: (a) Reduction with carbon (coke)

Answer: Option 1 — Reduction with carbon (coke)
Metals in themiddleof the activity series (like iron, zinc) are extracted byreducing their oxides with carbon (coke)in a blast furnace. (Highly reactive metals need electrolysis.) → Option 1.
RRB NTPC UG CBT-1 2025-26 – 20 June 2026 Shift 2 · Important non-metals and their facts

Q54. The dissolution of which of the following in water makes the solution acidic due to the formation of sulphurous acid?

  1. (a) Sulphur trioxide
  2. (b) Sulphonic acid
  3. (c) Sulphur hexafluoride
  4. (d) Sulphur dioxide
Answer & solution

Answer: (d) Sulphur dioxide

Topic: Acidic Oxides and Acid Formation
Sulphurous Acid Formation:
SO₂ + H₂O → H₂SO₃ (Sulphurous acid)
Key Facts:
• SO₂ (Sulphur dioxide) is an acidic oxide
• Dissolves in water to form H₂SO₃
• SO₃ forms H₂SO₄ (Sulphuric acid), not sulphurous
• SF₆ is inert and doesn't react with water
Answer: Option 4 → Sulphur dioxide
RRB NTPC UG CBT-1 2025-26 – 19 June 2026 Shift 2 · Physical properties of metals and non-metals

Q55. Which of the following elements is malleable and a good conductor of heat and electricity?

  1. (a) Sulfur (S)
  2. (b) Barium (Ba)
  3. (c) Iodine (I)
  4. (d) Neon (Ne)
Answer & solution

Answer: (b) Barium (Ba)

Topic:Properties of Elements
Metallic Properties:
• Malleability (can be hammered into sheets)
• Good conductor of heat and electricity
• These are characteristic properties of metals
Analysis of Options:
Sulfur (S) → Non-metal, brittle, poor conductor
Barium (Ba) →Metal, malleable, good conductor ✓
Iodine (I) → Non-metal, brittle, poor conductor
Neon (Ne) → Noble gas, no metallic properties
Answer: Option 2 → Barium (Ba)
SSC GD 2026 – 31 May 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q56. Copper reacts with moist carbon dioxide in the air, due to which its shiny brown surface gradually disappears and a ______ layer develops.

  1. (a) Green
  2. (b) Black
  3. (c) Red
  4. (d) Yellow
Answer & solution

Answer: (a) Green

Correct Answer: Green (Option 1)
When copper is exposed to moist air, it reacts with oxygen, water, and carbon dioxide to form basic copper carbonate (Cu2(OH)2CO3), also known as verdigris. This compound has a distinctive green colour and forms a protective patina on the surface of copper. This is why old copper statues, bronze monuments (like the Statue of Liberty), and copper roofs appear green over time.
Why others are wrong:
- Black: Iron forms a black oxide layer; copper does not produce a black patina in normal conditions.
- Red: Copper itself is reddish-brown; it does not form a red patina from this reaction.
- Yellow: No yellow compound is produced when copper reacts with moist CO2.
RRB NTPC UG CBT-1 2025-26 – 7 May 2026 Shift 3 · Chemical properties of metals

Q57. Which metal reacts violently with cold water, producing a metal hydroxide, hydrogen gas, and enough heat for the hydrogen to catch fire?

  1. (a) Potassium
  2. (b) Aluminium
  3. (c) Calcium
  4. (d) Magnesium
Answer & solution

Answer: (a) Potassium

Reactivity of Metals with Water
Potassium (K) is highly reactive alkali metal.
Reaction: 2K + 2H₂O → 2KOH + H₂ + Heat
Reactsviolentlywith cold water, releases enough heat to ignite H₂ gas.
Aluminium: Reacts with steam only.
Calcium: Reacts with cold water but less violently.
Magnesium: Reacts with hot water/steam.
Answer: Option 1 → Potassium
RRB NTPC GL CBT-1 2025-26 – 27 March 2026 Shift 3 · Physical properties of metals and non-metals

Q58. Which of the following elements in the periodic table is NOT classified as a metal?

  1. (a) Potassium
  2. (b) Calcium
  3. (c) Sulfur
  4. (d) Sodium
Answer & solution

Answer: (c) Sulfur

Classification of Elements:
Metals:Elements that lose electrons, conduct electricity, lustrous
Non-metals:Elements that gain electrons, poor conductors, dull
Analyzing options:
Potassium (K) → Alkali metal, Group 1
Calcium (Ca) → Alkaline earth metal, Group 2
Sulfur (S) → Non-metal, Group 16
Sodium (Na) → Alkali metal, Group 1
Sulfur is a yellow non-metal, poor conductor of heat and electricity
Answer: Option 3 → Sulfur
RRB NTPC GL CBT-1 2025-26 – 17 March 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q59. Which substance is the primary component of the reddish-brown coating formed on iron articles exposed to moist air?

  1. (a) Iron (II) Oxide ( FeO )
  2. (b) Iron (III) Hydroxide (Fe(OH)3)
  3. (c) Hydrated Iron (III) Oxide (Fe2O3·xH2O)
  4. (d) Iron Sulfate (FeSO4)
Answer & solution

Answer: (c) Hydrated Iron (III) Oxide (Fe2O3·xH2O)

When iron is exposed to moist air, it undergoes oxidation.
Process: Fe + O₂ + H₂O →Hydrated Iron (III) Oxide
This forms a reddish-brown coating calledrust.
Chemical formula:Fe₂O ₃· xH₂O(x = variable water molecules)
Answer: Option 3 → Hydrated Iron (III) Oxide ( Fe₂O ₃· xH₂O )
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 1 · Corrosion and its prevention (galvanisation, etc.)

Q60. A scientist observed that an iron railing near the sea corroded faster than the same type of railing in a dry city. What could the main reason be?

  1. (a) The sea air is more humid, diluting the rusting process.
  2. (b) The city air has less oxygen, preventing rust.
  3. (c) Sea air contains salt and moisture, which accelerates rusting.
  4. (d) The iron near the sea is exposed to more sunlight.
Answer & solution

Answer: (c) Sea air contains salt and moisture, which accelerates rusting.

Sea air contains salt and moisture.
Salt and moisture increase the rate of corrosion (rusting) of iron.
This accelerates the rusting process compared to dry city air.
Hence, the iron railing near the sea corrodes faster.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 3 · Chemical properties of metals

Q61. Identify the product formed when copper metal is exposed to dilute hydrochloric acid.

  1. (a) Salt and chlorine gas
  2. (b) Only Salt
  3. (c) Salt and hydrogen gas
  4. (d) No reaction
Answer & solution

Answer: (d) No reaction

Copper metal reacts with dilute hydrochloric acid.
Hydrochloric acid typically reacts with metals above hydrogen in the activity series to produce salt and hydrogen gas.
Copper is less reactive and does not produce chlorine gas in this reaction.
The product of copper and dilute hydrochloric acid is copper chloride (salt) and hydrogen gas.
Hence, the correct answer is salt and hydrogen gas.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 2 · Reactivity series

Q62. If A displaces B, and C displaces A, then the order of reactivity is:

  1. (a) B > A > C
  2. (b) C > B > A
  3. (c) C > A > B
  4. (d) A > B > C
Answer & solution

Answer: (c) C > A > B

If A displaces B, it means A is more reactive than B.
If C displaces A, it means C is more reactive than A.
Therefore, the order of reactivity is C > A > B.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 3 · Metallurgy - extraction and refining

Q63. In the electrolytic refining of copper, which of the following acts as the anode?

  1. (a) Copper sulphate solution
  2. (b) Carbon electrode
  3. (c) Pure copper plate
  4. (d) Impure copper block
Answer & solution

Answer: (d) Impure copper block

Option 4 is correct.
In electrolytic refining of copper, the impure copper block acts as the anode.
During electrolysis, copper from the impure anode dissolves into copper ions and deposits on the pure copper cathode.
Carbon electrode is generally used as an inert cathode in some processes but here pure copper plate is cathode, impure copper block is the anode.
Copper sulphate solution is the electrolyte, not the electrode.
Therefore, the anode is the impure copper block.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 2 · Ionic compounds and their properties

Q64. Which of the following are properties of ionic compounds?
A. High melting point
B. Soluble in non-polar solvents
C. Conduct electricity in solid state
D. Brittle in nature

  1. (a) Only (C) and (D)
  2. (b) Only (A) and (D)
  3. (c) Only (C) and (B)
  4. (d) Only (A) and (B)
Answer & solution

Answer: (b) Only (A) and (D)

The properties of ionic compounds include:
A. High melting point due to strong electrostatic forces between ions.
B. They are not soluble in non-polar solvents; they dissolve in polar solvents like water.
C. They do not conduct electricity in solid state; they conduct in molten or aqueous state.
D. Brittle nature because when layers shift, like charges repel causing the lattice to break.
Hence, only statements A and D are correct properties of ionic compounds.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 3 · Metallurgy - extraction and refining

Q65. Which of the following is the method used for refining metals such as copper, zinc and silver?

  1. (a) Smelting
  2. (b) Extraction
  3. (c) Distillation
  4. (d) Electrolytic refining
Answer & solution

Answer: (d) Electrolytic refining

Option 4 is correct: Electrolytic refining is the method commonly used to purify metals such as copper, zinc, and silver.
In this process, impure metal is made the anode, and pure metal is deposited on the cathode.
This technique removes impurities effectively and produces high-purity metals.
Other options are related to different metal processing stages:
Smelting is used to extract metal from ore.
Extraction is the overall process of obtaining metal from ore.
Distillation is used to separate mixtures based on boiling points, not for metal refining.
Hence, electrolytic refining is the best method for refining copper, zinc, and silver.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 1 · Metallurgy - extraction and refining

Q66. Which of the following methods is commonly used to extract metals low in the activity series, such as mercury and copper, from their ores?

  1. (a) Reduction with aluminium powder
  2. (b) Roasting
  3. (c) Electrolysis of molten ore
  4. (d) Displacement by carbon monoxide gas
Answer & solution

Answer: (b) Roasting

Metals low in activity series (Hg, Cu) are extracted byheating sulphide ores in air
This process is calledroasting
Example:
HgS → Hg + SO₂
Result: Roasting
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 1 · Reactivity series

Q67. Which of the following statements is true with respect to the reaction of a metal ‘A’ with metal ‘B’ of its solution, in which metal ‘A’ displaces metal ‘B’?

  1. (a) ‘A’ is more reactive than ‘B’.
  2. (b) Both ‘A’ and ‘B’ have the same reactivity.
  3. (c) The reaction cannot take place at all.
  4. (d) ‘B’ is more reactive than ‘A’.
Answer & solution

Answer: (a) ‘A’ is more reactive than ‘B’.

The metal 'A' displaces metal 'B' from its solution only if 'A' is more reactive than 'B'.
This is because a more reactive metal can replace a less reactive metal from its compound in the solution.
Hence, the correct statement is that 'A' is more reactive than 'B'.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 1 · Metallurgy - extraction and refining

Q68. Why is electrolysis used for the extraction of metals high up in the reactivity series, such as sodium and aluminum?

  1. (a) Because these metals have low melting points
  2. (b) Because these metals form volatile oxides
  3. (c) Because these metals cannot be reduced by carbon or hydrogen
  4. (d) Because these metals exist in native state
Answer & solution

Answer: (c) Because these metals cannot be reduced by carbon or hydrogen

Option 3 is correct.
Metals high in the reactivity series, such as sodium and aluminium, form very stable oxides due to their high reactivity.
These stable oxides cannot be reduced by carbon or hydrogen, which are common reducing agents in traditional extraction methods.
Therefore, electrolysis is used to extract these metals because it uses electrical energy to break down the compounds.
This process is effective where chemical reduction is not feasible for highly reactive metals.
Hence, electrolysis is necessary for isolating such metals from their ores.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 2 · Metallurgy - extraction and refining

Q69. During the extraction of metals from their ores, the removal of gangue is an important preliminary step. Which of the following statements most accurately explains why different concentration methods (such as hydraulic washing, froth flotation and magnetic separation) are used for different ores?

  1. (a) Because gangue particles are chemically reactive and must be removed by oxidation before extraction
  2. (b) Because each method exploits specific differences in physical and chemical properties between the ore and the gangue
  3. (c) Because the choice of concentration method depends on the melting point of the ore and gangue
  4. (d) Because all ores have identical physical properties but different chemical compositions
Answer & solution

Answer: (b) Because each method exploits specific differences in physical and chemical properties between the ore and the gangue

Option 2 is correct.
Different concentration methods are used because they exploit specific differences between the ore and gangue.
These differences can be in physical properties like density, magnetic susceptibility, or surface properties.
Hydraulic washing uses density differences.
Froth flotation exploits surface chemistry differences.
Magnetic separation depends on magnetic properties.
Hence, method choice depends on ore and gangue characteristics.
Option 1 is incorrect because gangue removal is physical, not by oxidation.
Option 3 is incorrect as melting points are not a deciding factor for concentration.
Option 4 is wrong; ores differ in physical properties too.
Therefore, option 2 best explains why different methods are used.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 3 · Metallurgy - extraction and refining

Q70. In the process of electrolytic refining of copper, which of the following is correctly matched?

  1. (a) Anode – Pure copper
  2. (b) Cathode Mud – Pure copper crystals
  3. (c) Electrolyte – Acidified Copper sulphate solution
  4. (d) Cathode – Impure copper
Answer & solution

Answer: (c) Electrolyte – Acidified Copper sulphate solution

In electrolytic refining of copper, the electrolyte used is Acidified Copper sulphate solution.
Anode is impure copper, which dissolves into the electrolyte.
Cathode is pure copper where copper ions deposit as pure copper crystals.
Cathode Mud contains impurities that fall off the anode and do not dissolve.
Hence, option 3 is correctly matched.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 3 · Metallurgy - extraction and refining

Q71. Metals in the middle of the activity series, such as iron and zinc, are generally extracted by:

  1. (a) Electrolysis of molten salts
  2. (b) Heating alone without any reducing agent
  3. (c) Displacement from aqueous solution
  4. (d) Reduction of their oxides with carbon or carbon monoxide
Answer & solution

Answer: (d) Reduction of their oxides with carbon or carbon monoxide

Metals like iron and zinc lie in the middle of the activity series.
They are less reactive than aluminium and sodium but more reactive than copper and silver.
Such metals are typically extracted by reducing their oxides using a suitable reducing agent.
Carbon or carbon monoxide are common reducing agents used for these metals.
This method is economical and effective for metals that cannot be extracted by heating alone or electrolysis.
Hence, the correct extraction method is reduction of their oxides with carbon or carbon monoxide.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 3 · Corrosion and its prevention (galvanisation, etc.)

Q72. Which of the following is the best method to prevent corrosion of iron in coastal areas?

  1. (a) Heating the iron periodically
  2. (b) Painting with oil-based paints
  3. (c) Galvanisation
  4. (d) Immersing in cold water
Answer & solution

Answer: (c) Galvanisation

Corrosion of iron is accelerated in coastal areas due to high moisture and salt content in the air.
The best prevention method is galvanisation, which involves coating iron with a layer of zinc.
Zinc reacts preferentially and protects the iron from rusting even if the coating is damaged.
Heating does not prevent corrosion effectively in coastal climates.
Painting with oil-based paints can delay corrosion but is less durable in salty air.
Immersing in cold water does not prevent corrosion and may promote it.
Hence, galvanisation is the most effective method in coastal environments.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 1 · Chemical properties of metals

Q73. Which of the following metals forms an amphoteric oxide when reacting with air?

  1. (a) Potassium
  2. (b) Sodium
  3. (c) Calcium
  4. (d) Aluminium
Answer & solution

Answer: (d) Aluminium

Correct option is 4: Aluminium.
Aluminium reacts with air forming aluminium oxide (Al2O3).
Aluminium oxide is amphoteric − it can react with both acids and bases.
Potassium, sodium, and calcium oxides are strongly basic, not amphoteric.
Hence, aluminium forms an amphoteric oxide on reacting with air.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 1 · Reactivity series

Q74. Which of the following statements correctly explains the position of sodium (Na) in the activity series of metals?

  1. (a) Sodium is less reactive than copper and cannot displace it from salt solution.
  2. (b) Sodium does not react with water, hence placed at the bottom of the series.
  3. (c) Sodium is less reactive than hydrogen and hence placed below it.
  4. (d) Sodium is more reactive than hydrogen and displaces it from acid.
Answer & solution

Answer: (d) Sodium is more reactive than hydrogen and displaces it from acid.

Sodium (Na) is a highly reactive metal.
It is more reactive than hydrogen in the activity series.
Hence, sodium can displace hydrogen from acids during chemical reactions.
This is why sodium is placed above hydrogen in the activity series of metals.
Therefore, Option 4 is the correct explanation.
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Chemical properties of metals

Q75. A clean strip of calcium metal is added to cold water and the reaction is observed. Compared to sodium and magnesium, which of the following statements correctly describes calcium’s reactivity and the nature of products formed?

  1. (a) Calcium reacts explosively like sodium, forming calcium hydroxide and hydrogen gas.
  2. (b) Calcium reacts slowly with cold water, producing calcium oxide and oxygen gas.
  3. (c) Calcium reacts less vigorously than sodium but more than magnesium, forming calcium hydroxide and hydrogen gas.
  4. (d) Calcium does not react with cold water but only with steam, forming calcium oxide and hydrogen gas.
Answer & solution

Answer: (c) Calcium reacts less vigorously than sodium but more than magnesium, forming calcium hydroxide and hydrogen gas.

Calcium reacts with cold water, but less vigorously than sodium and more than magnesium.
The reaction produces calcium hydroxide (Ca(OH)2) and hydrogen gas (H2).
Sodium reacts explosively with cold water forming sodium hydroxide and hydrogen gas.
Magnesium reacts very slowly with cold water.
Thus, calcium's reactivity is moderate between sodium and magnesium, with the formation of calcium hydroxide and hydrogen gas.
This matches option 3 correctly.
Final answer: Option 3
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Metallurgy - extraction and refining

Q76. Dhritiman tries to extract magnesium from magnesium oxide using carbon. The attempt fails. What is the reason?

  1. (a) Magnesium forms a volatile compound with carbon.
  2. (b) Carbon is less reactive than magnesium.
  3. (c) Carbon reacts violently with oxygen.
  4. (d) The reaction produces carbon monoxide only.
Answer & solution

Answer: (b) Carbon is less reactive than magnesium.

Magnesium is more reactive than carbon.
Therefore, carbon cannot reduce magnesium oxide to magnesium metal.
Because carbon is less reactive, it cannot displace magnesium from its oxide.
Hence, the attempt to extract magnesium using carbon fails.
Final answer: Option 2
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 2 · Reactivity series

Q77. Four test tubes contain solutions of CuSO₄, MgSO₄, ZnSO₄, and AgNO₃. A student adds zinc metal to each test tube. In which test tube(s) will a reaction occur?

  1. (a) CuSO₄ and AgNO₃ only
  2. (b) ZnSO₄ only
  3. (c) With all solutions
  4. (d) CuSO₄ only
Answer & solution

Answer: (a) CuSO₄ and AgNO₃ only

Zinc is more reactive than copper and silver but not more reactive than magnesium or zinc itself.
When zinc metal is added to CuSO₄ (copper sulfate), zinc displaces copper from the solution causing a reaction.
Similarly, zinc displaces silver from AgNO₃ (silver nitrate) because zinc is more reactive than silver.
No reaction occurs with MgSO₄ because magnesium is more reactive than zinc.
No reaction occurs with ZnSO₄ since zinc cannot displace itself.
Therefore, reaction occurs only in test tubes containing CuSO₄ and AgNO₃.
Final answer: Option 1
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Chemical properties of metals

Q78. When potassium reacts with water, we observe:

  1. (a) No visible change
  2. (b) Gentle bubbling and slow reaction
  3. (c) Formation of a greenish compound
  4. (d) Bright flame and rapid reaction
Answer & solution

Answer: (d) Bright flame and rapid reaction

Potassium is a highly reactive alkali metal.
When potassium reacts with water, it reacts vigorously.
This reaction produces potassium hydroxide and hydrogen gas.
The hydrogen gas ignites due to the heat, causing a bright flame.
Hence, we observe a bright flame and a rapid reaction when potassium reacts with water.
Final answer: Option 4
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 3 · Corrosion and its prevention (galvanisation, etc.)

Q79. Which method involves coating iron with a layer of zinc to protect it from rusting?

  1. (a) Galvanisation
  2. (b) Painting
  3. (c) Electroplating
  4. (d) Tinning
Answer & solution

Answer: (a) Galvanisation

The process of coating iron with a layer of zinc is called Galvanisation.
Zinc acts as a protective layer, preventing rusting of iron even if the coating gets scratched.
This protection is due to zinc's higher reactivity, which corrodes first instead of iron.
Hence, Galvanisation is the standard industrial method for rust protection of iron and steel.
Final answer: Option 1
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 2 · Physical properties of metals and non-metals

Q80. Which of the following non-metals is a good conductor of electricity in the solid state due to the presence of delocalized electrons within its crystal lattice?

  1. (a) Iodine
  2. (b) Phosphorus
  3. (c) Sulphur
  4. (d) Graphite
Answer & solution

Answer: (d) Graphite

Correct option is 4: Graphite.
Graphite is a non-metal but conducts electricity in solid state due to delocalised electrons in its layered crystal structure.
These delocalised electrons are free to move, allowing electrical conduction.
Iodine, phosphorus and sulphur do not have such delocalised electrons and are poor conductors in solid form.
Hence, graphite is unique among the given options for conducting electricity in solid state.
Final answer: Option 4
RRB JE CBT-1 2025-26 – 25 February 2026 Shift 3 · Metallurgy - extraction and refining

Q81. Why are metals such as sodium and calcium extracted by electrolytic reduction instead of heating with carbon?

  1. (a) They have greater affinity for oxygen than carbon
  2. (b) They decompose when heated with carbon
  3. (c) They form unstable oxides at high temperature
  4. (d) They exist only as molten chlorides in nature
Answer & solution

Answer: (a) They have greater affinity for oxygen than carbon

Solution:
Metals likesodium and calcium are highly reactive
They havegreater affinity for oxygen than carbon
So carbon cannot reduce their oxides
Answer: They have greater affinity for oxygen than carbon
RRB JE CBT-1 2025-26 – 25 February 2026 Shift 3 · Metallurgy - extraction and refining

Q82. Why are sulphide ores usually converted into oxides before the extraction of metals?

  1. (a) Sulphide ores contain more gangue materials
  2. (b) Metal oxides are easier to reduce than sulphides
  3. (c) Metal sulphides react faster with carbon
  4. (d) Sulphide ores are unstable at room temperature
Answer & solution

Answer: (b) Metal oxides are easier to reduce than sulphides

Solution:
In metallurgy,sulphide ores are first roasted to form oxides
Metal oxides are easier to reduce(by carbon or other reducing agents) than sulphides
Direct reduction of sulphides is difficult and inefficient
Answer: Metal oxides are easier to reduce than sulphides
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 1 · Chemical properties of metals

Q83. Magnesium ribbon burns with:

  1. (a) A bright white flame
  2. (b) A yellow luminous flame
  3. (c) A blue non-luminous flame
  4. (d) No visible flame
Answer & solution

Answer: (a) A bright white flame

Magnesium ribbon burns in air with a bright white flame.
This is due to the high temperature of burning magnesium and the formation of magnesium oxide.
Hence, the correct observation is a bright white flame.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 3 · Metallurgy - extraction and refining

Q84. What happens to insoluble impurities during electrolytic refining?

  1. (a) They dissolve completely
  2. (b) They settle as anode mud
  3. (c) They deposit on cathode
  4. (d) They evaporate
Answer & solution

Answer: (b) They settle as anode mud

In electrolytic refining, the impure metal acts as the anode.
When current passes, the pure metal dissolves and deposits at the cathode.
Insoluble impurities do not dissolve; instead, they settle down at the bottom.
This residue collected at the bottom of the anode is called anode mud or anode slime.
Hence, insoluble impurities settle as anode mud during the process.
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 1 · Reactivity series

Q85. Which metal listed below shows the strongest reaction when added to dilute hydrochloric acid?

  1. (a) Iron
  2. (b) Copper
  3. (c) Zinc
  4. (d) Magnesium
Answer & solution

Answer: (d) Magnesium

Option 4 is correct: Magnesium shows the strongest reaction with dilute hydrochloric acid.
Magnesium reacts vigorously with dilute HCl producing hydrogen gas rapidly.
The reaction strength order with dilute HCl is generally: Magnesium > Zinc > Iron > Copper.
Copper does not react with dilute hydrochloric acid as it is less reactive than hydrogen.
Therefore, Magnesium is the most reactive metal among the options given when added to dilute hydrochloric acid.
This is a common question tested in competitive exams to check reactivity series knowledge.
Hence, the strongest reaction is observed with Magnesium.
Final answer: Option 4
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 2 · Chemical properties of metals

Q86. Equal pieces of zinc and copper are added separately to dilute sulphuric acid. Which observation is CORRECT?

  1. (a) Both metals evolve hydrogen gas
  2. (b) Only zinc evolves hydrogen gas
  3. (c) Neither metal evolves hydrogen gas
  4. (d) Only copper evolves hydrogen gas
Answer & solution

Answer: (b) Only zinc evolves hydrogen gas

Zinc is a reactive metal and reacts with dilute sulphuric acid.
This reaction produces hydrogen gas along with zinc sulphate.
Copper is less reactive and does not react with dilute sulphuric acid to evolve hydrogen.
Therefore, only zinc evolves hydrogen gas in this reaction.
Final answer: Option 2
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 3 · Corrosion and its prevention (galvanisation, etc.)

Q87. Iron nails are coated with zinc to prevent rusting. Even if the zinc layer is scratched, rusting does not occur because —

  1. (a) Zinc forms a hard oxide layer.
  2. (b) Iron becomes stainless in the presence of zinc.
  3. (c) Zinc reacts with moisture to form a protective film
  4. (d) Zinc acts as a sacrificial anode and corrodes instead of iron.
Answer & solution

Answer: (d) Zinc acts as a sacrificial anode and corrodes instead of iron.

Correct option: 4
Zinc coating on iron nails prevents rusting by acting as a sacrificial anode.
When the zinc layer is scratched, zinc corrodes preferentially instead of iron.
This sacrificial corrosion protects the iron beneath from rusting.
Hence, even if zinc coating is damaged, iron remains protected from rust.
Answer is option 4.
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 3 · Reactivity series

Q88. Which metal releases the most heat when reacting with excess hydrochloric acid?

  1. (a) Magnesium
  2. (b) Iron
  3. (c) Zinc
  4. (d) Nickel
Answer & solution

Answer: (a) Magnesium

Magnesium releases the most heat when reacting with excess hydrochloric acid.
This is because magnesium is more reactive compared to iron, zinc, and nickel.
Greater reactivity means a more vigorous and exothermic reaction with HCl.
Hence, magnesium produces the maximum heat among the given metals.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 1 · Metallurgy - extraction and refining

Q89. Which of the following metals is NOT refined by electrolytic refining?

  1. (a) sodium
  2. (b) copper
  3. (c) tin
  4. (d) zinc
Answer & solution

Answer: (a) sodium

Correct option: 1
Sodium is not refined by electrolytic refining.
Sodium is highly reactive and is usually refined by other methods like the Downs process.
Copper, tin, and zinc are commonly refined using electrolytic refining to achieve high purity.
Thus, sodium stands out as the metal not refined electrolytically.
Answer explained and clear.
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 3 · Metallurgy - extraction and refining

Q90. Which process is used to convert zinc carbonate ore into zinc oxide before reduction?

  1. (a) Heating with aluminium powder
  2. (b) Heating with carbon powder
  3. (c) Heating strongly in limited air
  4. (d) Heating strongly in excess air
Answer & solution

Answer: (c) Heating strongly in limited air

Zinc carbonate is converted to zinc oxide by heating.
This process is called roasting.
Roasting means heating strongly in limited air.
Hence, option 3 is correct.
Final answer: Option 3
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 3 · Metallurgy - extraction and refining

Q91. Why is mercury obtained from cinnabar ore through two heating steps instead of direct reduction?

  1. (a) Mercury sulphide must first change into oxide
  2. (b) Mercury sulphide melts before decomposition
  3. (c) Mercury metal reacts with oxygen on heating
  4. (d) Mercury oxide forms only in absence of air
Answer & solution

Answer: (a) Mercury sulphide must first change into oxide

Mercury is obtained from cinnabar ore (mercury sulphide, HgS) by heating in presence of air.
First, mercury sulphide is converted to mercury oxide (HgO) by partial oxidation.
This step is necessary because direct reduction is not efficient.
Then, mercury oxide decomposes to mercury metal and oxygen upon further heating.
Hence, the two-step heating helps in converting HgS to HgO first, and then to metallic mercury.
So, mercury sulphide must first change into oxide before mercury is obtained.
Final answer: Option 1
SSC MTS 2025 – 6 February 2026 Shift 1 · Important metals and their facts

Q92. _____ is the second most used metal in the world after steel.

  1. (a) Aluminum
  2. (b) Zinc
  3. (c) Nickel
  4. (d) Lead
Answer & solution

Answer: (a) Aluminum

Correct Answer: 1 (Aluminum)
Aluminum is the second most used metal in the world after steel (iron). It is widely used due to its lightweight properties, corrosion resistance, electrical conductivity, and recyclability. Major applications include aerospace, construction, packaging (cans, foils), and transportation.
Option 2 (Zinc) is incorrect - Zinc is an important metal used mainly for galvanization but is not the second most used overall.
Option 3 (Nickel) is incorrect - Nickel is used in alloys and batteries but is not the second most used metal.
Option 4 (Lead) is incorrect - Lead usage has declined due to environmental concerns and is not the second most used metal.
SSC MTS 2025 – 6 February 2026 Shift 2 · Occurrence of metals - ores and minerals

Q93. Which of the following is an ore of mercury?

  1. (a) Bauxite
  2. (b) Magnetite
  3. (c) Cinnabar
  4. (d) Malachite
Answer & solution

Answer: (c) Cinnabar

Correct Answer: 3 (Cinnabar)
Cinnabar (HgS - mercuric sulphide) is the primary ore of mercury. It is a bright red mineral and the most important source of mercury worldwide.
Option 1 (Bauxite) is incorrect - Bauxite is the primary ore of Aluminium.
Option 2 (Magnetite) is incorrect - Magnetite (Fe3O4) is an ore of Iron.
Option 4 (Malachite) is incorrect - Malachite is a copper carbonate mineral and is an ore of Copper.
Delhi Police Constable (Exe) 2025-26 – 3 January 2026 Shift 2 · Occurrence of metals - ores and minerals

Q94. Bauxite is the primary ore used to produce which metal?

  1. (a) Iron
  2. (b) Copper
  3. (c) Aluminium
  4. (d) Zinc
Answer & solution

Answer: (c) Aluminium

Bauxite is the primary ore from which aluminium is extracted. Through the Bayer process, aluminium oxide (alumina) is first obtained from bauxite, and then aluminium metal is produced via electrolysis (Hall- Heroult process). India has large bauxite deposits in Odisha, Jharkhand, and Gujarat.
(a) Incorrect: Iron is extracted from iron ore (hematite, magnetite), not bauxite.
(b) Incorrect: Copper is extracted from copper ores like chalcopyrite (copper pyrite), not bauxite.
(c) Incorrect: Zinc is extracted from zinc ores like sphalerite (zinc sulphide ), not bauxite.
SSC CGL Tier-1 2025 – 13 September 2025 Shift 1 · Physical properties of metals and non-metals

Q95. Why are cooking utensils often made with a copper bottom?

  1. (a) Copper is a good insulator, preventing heat loss
  2. (b) Copper has a low melting point, making it easy to manufacture
  3. (c) Copper is a good conductor of heat, ensuring even heating
  4. (d) Copper reacts readily with food, enhancing flavour
Answer & solution

Answer: (c) Copper is a good conductor of heat, ensuring even heating

Copper has very high thermal conductivity (among the best of common metals).
A copper bottom therefore distributes heat quickly and evenly across the base of the utensil, preventing hot spots and ensuring food cooks uniformly.
Copper is not an insulator; its melting point is fairly high (~1084 °C), so ease of manufacture is not the reason; and food contact with copper is actually limited (which is why copper utensils are usually tinned or used only at the bottom).
Hence the correct reason is: copper is a good conductor of heat.
RRB NTPC UG CBT-1 2024-25 – 8 September 2025 Shift 3 · Important non-metals and their facts

Q96. Which element from Group 17 is used to eliminate bacteria and viruses from surfaces, drinking water, sewage, industrial waste, and swimming pools and spas?

  1. (a) Bromine
  2. (b) Chlorine
  3. (c) Fluorine
  4. (d) Iodine
Answer & solution

Answer: (b) Chlorine

RRB NTPC UG CBT-1 2024-25 – 13 August 2025 Shift 3 · Alloys and their composition

Q97. Why is an alloy considered a mixture even though it cannot be separated by physical methods?

  1. (a) It is formed only by non-metals.
  2. (b) It contains only one type of element in vapor form.
  3. (c) It shows the properties of its constituents and can have variable composition.
  4. (d) Alloys are always magnetic because they contain metals with a fixed composition.
Answer & solution

Answer: (c) It shows the properties of its constituents and can have variable composition.

RRB NTPC UG CBT-1 2024-25 – 11 August 2025 Shift 2 · Metallurgy - extraction and refining

Q98. Which method used in metallurgy specifically describes the formation of metal oxides by heating carbonate ores?

  1. (a) Calcination
  2. (b) Carbonation
  3. (c) Calcification
  4. (d) Chlorination
Answer & solution

Answer: (a) Calcination

RRB Technician Grade III 2024-25 – 30 December 2024 Shift 1 · Chemical properties of metals

Q99. Zinc metal reacts with sodium hydroxide to produce _______.

  1. (a) sodium zincate
  2. (b) zinc hydroxide
  3. (c) zinc oxide
  4. (d) sodium hydride
Answer & solution

Answer: (a) sodium zincate

Correct Answer: Option 1 — sodium zincate
Metals normally do not react with bases. Zinc is one of the few exceptions, because it is an amphoteric metal — it reacts both with acids and with strong alkalis. When zinc is heated with sodium hydroxide solution it dissolves, forming the salt sodium zincate (Na₂ZnO₂) and liberating hydrogen gas.
The reaction happens because zinc's oxide layer, ZnO, is amphoteric: it can behave as a base towards an acid and as an acid towards an alkali. Aluminium behaves in the same way, giving sodium aluminate. The H₂ given off burns with a pop sound, the standard laboratory test.
⚗️ The Reaction
Zn(s) + 2NaOH(aq) → Na₂ZnO₂(aq) + H₂(g)
• The product Na₂ZnO₂ is sodium zincate; hydrogen is set free.
• Atoms balance: Zn 1 = 1, Na 2 = 2, O 2 = 2, H 2 = 2.
• With an acid the same metal gives a different salt: Zn + 2HCl → ZnCl₂ + H₂ — this double behaviour is what amphoteric means.
❌ Why the other options are incorrect
✗ zinc hydroxide — Zn(OH)₂ is formed when a zinc salt (say ZnSO₄) meets a small amount of NaOH, as a white precipitate; with excess NaOH it dissolves again to sodium zincate. Zinc metal does not stop at the hydroxide.
✗ zinc oxide — ZnO is made by burning zinc in air (2Zn + O₂ → 2ZnO) or by heating zinc carbonate; no alkali is involved.
✗ sodium hydride — NaH is an ionic hydride made by heating sodium metal in hydrogen gas; sodium here is already fixed in NaOH and is not reduced by zinc to a hydride.
📌 SSC & Railway Exam Facts
• Zn + 2NaOH → Na₂ZnO₂ + H₂↑ (sodium zincate); 2Al + 2NaOH + 2H₂O → 2NaAlO₂ + 3H₂↑ (sodium aluminate).
• Amphoteric metals/oxides: Zn, Al, Pb, Sn — ZnO, Al₂O₃, PbO, SnO.
• Galvanisation is coating iron with a layer of zinc to prevent rusting.
• Zinc's place in the reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au.
• Hydrogen gas burns with a pop sound — the standard test in the laboratory.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 1 · Chemical properties of metals

Q100. Which of the following oxides is amphoteric in nature?

  1. (a) Copper oxide
  2. (b) Aluminium oxide
  3. (c) Sodium peroxide
  4. (d) Calcium oxide
Answer & solution

Answer: (b) Aluminium oxide

Correct Answer: Option 2 — Aluminium oxide
An amphoteric oxide is one that shows both basic and acidic behaviour — it reacts with acids like a base, and with bases (alkalis) like an acid, giving a salt and water in each case.
Aluminium oxide (Al₂O₃) is the standard example. With hydrochloric acid it behaves as a base and gives aluminium chloride; with sodium hydroxide it behaves as an acid and gives sodium aluminate. This is why the thin, tough layer of Al₂O₃ that forms on aluminium metal dissolves in both acids and alkalis. Zinc oxide (ZnO) behaves in exactly the same way.
⚗️ The Reactions
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O *(acts as a base)*
Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O *(acts as an acid)*
• With an acid it gives the salt AlCl₃; with an alkali it gives sodium aluminate (NaAlO₂).
• Reacting with both an acid and a base is precisely what makes an oxide amphoteric.
• The same duality is seen with ZnO: ZnO + 2HCl → ZnCl₂ + H₂O and ZnO + 2NaOH → Na₂ZnO₂ + H₂O.
❌ Why the other options are incorrect
✗ Copper oxide — CuO is a basic oxide of the metal copper; it dissolves in acids (CuO + 2HCl → CuCl₂ + H₂O) but does not react with alkalis such as NaOH.
✗ Sodium peroxide — Na₂O₂ is a peroxide of a highly reactive alkali metal and is strongly basic (with water it gives NaOH and O₂); a peroxide is not the same thing as an amphoteric oxide.
✗ Calcium oxide — CaO (quicklime) is a typical basic oxide; with water it gives the base Ca(OH)₂, and it reacts only with acids, never with alkalis.
📌 SSC & Railway Exam Facts
• Amphoteric oxides: Al₂O₃, ZnO, PbO, SnO, BeO — they react with both acids and bases.
• Metal oxides are basic, non-metal oxides are acidic; CO, NO and H₂O are neutral oxides.
• The ore of aluminium is bauxite (Al₂O₃·2H₂O); the metal is extracted by the Hall–Héroult electrolytic process.
• Anodising deliberately thickens the Al₂O₃ layer to protect aluminium from corrosion.
• Corundum is crystalline Al₂O₃; ruby and sapphire are its coloured forms.
12

More Chemistry chapters

Acids, Bases and Salts172 questionsCarbon and its Compounds167 questionsChemical Reactions and Equations131 questionsStructure of Atom104 questionsMixtures, Solutions and Separation104 questionsAtoms, Molecules and Mole Concept100 questionsEnvironmental Chemistry89 questionsMatter and its States80 questionsPeriodic Classification of Elements56 questionsEveryday and Industrial Chemistry52 questionsChemistry Miscellaneous20 questionsChemical Bonding9 questionsPhysical Chemistry6 questions
📥 PDF of this paper (all subjects, English & Hindi): All previous year papers PDF · ▶ Attempt previous year papers as free online tests · 🏆 Free live mock tests · 📰 Daily current affairs quiz