Q1. Which of the following is example of synthetic indicator?
I. Methyl orange
II. Phenolphthalein
- (a) Only I
- (b) Only II
- (c) Both I and II
- (d) Neither I nor II
Answer & solution
Answer: (c) Both I and II
Synthetic indicators are artificially prepared chemical substances used to detect the acidic or basic nature of a solution by changing colour . Both Methyl orange (I) and Phenolphthalein (II) are synthetic indicators.
Methyl orange: turns red in acidic solutions and yellow in basic solutions.
Phenolphthalein: remains colourless in acidic/neutral solutions and turns pink/magenta in basic solutions.
Options 1 (Only I) and 2 (Only II) are incorrect as both are synthetic indicators. Option 4 (Neither) is incorrect.