NEET (UG)

Practice Test 1 — Aldehydes, Ketones and Carboxylic Acids

12 questions • 18 minutes • auto-graded with full solutions

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Section A — MCQ (Single Correct & Statement-based)

Question 1

The carbonyl carbon is:

Solution: $sp^2$, planar carbonyl.

Question 2

Towards nucleophilic addition the order is:

Solution: Aldehydes more reactive than ketones.

Question 3

A silver mirror forms with:

Solution: Aldehydes give a positive Tollens' test.

Question 4

Statements: (I) Benzaldehyde gives the Cannizzaro reaction. (II) Benzaldehyde has alpha-hydrogens. Which is/are correct?

Solution: I correct; II wrong — benzaldehyde has NO alpha-H, which is why it gives Cannizzaro.

Question 5

A positive iodoform test is NOT given by:

Solution: Methanol lacks the $\text{CH}_3\text{CH(OH)–}$ group.

Question 6

The strongest acid among these is:

Solution: EWG chlorines make trichloroacetic acid strongest.

Question 7

To distinguish a carboxylic acid from a phenol, use:

Solution: Only the acid liberates $\text{CO}_2$ from bicarbonate.

Question 8

Reaction of $\text{RMgX}$ with $\text{CO}_2$ then $\text{H}^+$ gives a product with:

Solution: $\text{CO}_2$ adds one carbon as $-\text{COOH}$.

Section B — Assertion & Reason

Question 9

A: Aldehydes are more reactive than ketones towards nucleophiles.
R: The two alkyl groups of a ketone increase the positive charge on the carbonyl carbon.

Solution: A is true, but R is false — the alkyl groups DECREASE (not increase) the positive charge, so R is wrong.

Question 10

A: Carboxylic acids are more acidic than phenols.
R: The carboxylate ion is resonance-stabilised over two oxygen atoms.

Solution: Equal sharing of charge over two oxygens is exactly why the acid is stronger — R explains A.

Question 11

A: Benzaldehyde does not give a positive iodoform test.
R: Benzaldehyde has no $\text{CH}_3\text{CO–}$ or $\text{CH}_3\text{CH(OH)–}$ group.

Solution: The iodoform test needs a methyl-keto/methyl-carbinol group, which benzaldehyde lacks — R explains A.

Question 12

A: Trichloroacetic acid is a stronger acid than acetic acid.
R: The three electron-withdrawing chlorine atoms stabilise the trichloroacetate ion.

Solution: The electron-withdrawing chlorines stabilise the conjugate base, making the acid stronger — R explains A.