The diagrams show the structures of two esters, X and Y, that are formed in ripening apples.
Which carboxylic acids are formed when these esters are hydrolysed by H₂SO₄ (aq)? 
▶️ Answer/Explanation
Ans: B
Hydrolysis of Esters X and Y:
• Ester X (methyl butanoate) hydrolyzes to butanoic acid and methanol.
• Ester Y (ethyl propanoate) hydrolyzes to propanoic acid and ethanol.
Why Option B is Correct:
The image in option B shows the correct carboxylic acids (butanoic acid and propanoic acid) formed from the hydrolysis of X and Y, respectively. The other options either show incorrect acids or mismatch the structures.
P is a carboxylic acid with molecular formula \(C_5H_{10}O_2\). Carboxylic acid P reacts with an excess of \(LiAlH_4\) to form compound Q. Which pairs of molecules could be carboxylic acid P and compound Q?
▶️ Answer/Explanation
Ans: D
1. Reaction Mechanism: \(LiAlH_4\) reduces carboxylic acids (\(RCOOH\)) to primary alcohols (\(RCH_2OH\)).
2. Analysis of Options: – Option 1 (Pentanoic acid) would reduce to 1-pentanol, but 1-pentanol isn’t shown as product 2. – Option 2 (3-methylbutanoic acid) would reduce to 3-methylbutan-1-ol, but this isn’t shown as product 3. – Option 3 (2,2-dimethylpropanoic acid) correctly reduces to 2,2-dimethylpropan-1-ol (product 3).
3. Conclusion: Only Option 3 correctly shows both the carboxylic acid and its corresponding alcohol product, making D the correct answer.
The product of the reaction between propanone and hydrogen cyanide is hydrolysed under acidic conditions. What is the formula of the final product?
▶️ Answer/Explanation
Ans: D
Step 1: Reaction with HCN
Propanone (CH₃COCH₃) reacts with HCN to form a cyanohydrin: (CH₃)₂C(OH)CN.
Which reagent gives a positive result with propanone?
▶️ Answer/Explanation
Ans: A
1. Iodoform Test (Alkaline \(I_2\)): Propanone (a methyl ketone) reacts with alkaline \(I_2\) to form a yellow precipitate of iodoform (\(CHI_3\)), giving a positive test. 2. Other Reagents: – B (Aqueous bromine): No reaction with propanone. – C (Fehling’s) and D (Tollens’): Only react with aldehydes, not ketones like propanone. Thus, only alkaline \(I_2\)(aq) (Option A) gives a positive result.