Q94 / 180 · NEET 2026 (Cancelled) · Chemistry
In a test tube containing a salt, a few drops of dilute $\text{H}_2\text{SO}_4$ was added, which gave colourless vapours having the smell of vinegar. The vapours turned the blue litmus paper red. Identify the correct anion from the following :
- ASulphide, $\text{S}^{2-}$
- BSulphate, $\text{SO}_4^{2-}$
- Correct answerCAcetate, $\text{CH}_3\text{COO}^{-}$
- DCarbonate, $\text{CO}_3^{2-}$
Solution
When a salt containing the acetate anion ($\text{CH}_3\text{COO}^{-}$) is treated with dilute $\text{H}_2\text{SO}_4$, acetic acid ($\text{CH}_3\text{COOH}$) is formed.
$2\text{CH}_3\text{COO}^{-} + \text{H}_2\text{SO}_4 \rightarrow 2\text{CH}_3\text{COOH} + \text{SO}_4^{2-}$
Acetic acid vapours are colourless and have a characteristic smell of vinegar. Being acidic in nature, these vapours turn blue litmus paper red.
Sulphide ($\text{S}^{2-}$) gives $\text{H}_2\text{S}$ gas which has a rotten egg smell.
Sulphate ($\text{SO}_4^{2-}$) does not react with dilute $\text{H}_2\text{SO}_4$.
Carbonate ($\text{CO}_3^{2-}$) gives $\text{CO}_2$ gas which is odourless.
Answer: Acetate, $\text{CH}_3\text{COO}^{-}$
$2\text{CH}_3\text{COO}^{-} + \text{H}_2\text{SO}_4 \rightarrow 2\text{CH}_3\text{COOH} + \text{SO}_4^{2-}$
Acetic acid vapours are colourless and have a characteristic smell of vinegar. Being acidic in nature, these vapours turn blue litmus paper red.
Sulphide ($\text{S}^{2-}$) gives $\text{H}_2\text{S}$ gas which has a rotten egg smell.
Sulphate ($\text{SO}_4^{2-}$) does not react with dilute $\text{H}_2\text{SO}_4$.
Carbonate ($\text{CO}_3^{2-}$) gives $\text{CO}_2$ gas which is odourless.
Answer: Acetate, $\text{CH}_3\text{COO}^{-}$
Hence, the correct answer is option: 'C'.