Consider the given reaction, identify 'X' and 'Y' :

Solution

Chemistry ma’am · 4 steps

Base makes the cyanide ion that attacks the C=O, and LiAlH4 turns the C≡N into CH2NH2.

1. Choosing X. HCN is a weak acid, so on its own it gives very little CN⁻. A base such as NaOH pulls off the proton and makes CN⁻, the nucleophile that attacks the carbonyl carbon. An acid like HNO₃ would push the equilibrium back and suppress CN⁻.
2. Cyanohydrin forms. CN⁻ adds to the C=O carbon of 2-methylbutanal, and the alkoxide picks up H⁺ from water. This gives CH₃CH₂CH(CH₃)CH(OH)CN, which has 6 carbons because the CN brings one carbon in.
3. Choosing Y. LiAlH₄ followed by H₃O⁺ adds four H atoms across the C≡N triple bond and turns it into CH₂NH₂. The OH group is not touched, and the nitrile carbon stays in the chain.

   CH₃CH₂CH(CH₃)CH(OH)C≡N →(1. LiAlH₄, 2. H₃O⁺) CH₃CH₂CH(CH₃)CH(OH)CH₂NH₂

   Option	X	Y	Verdict
   (a)	NaOH, correct	NH₂ and OH on one carbon, only 5 C	wrong Y
   (b)	HNO₃, wrong	1-amino-3-methylpentan-2-ol	wrong X
   (c)	NaOH, correct	1-amino-3-methylpentan-2-ol	both correct
   (d)	HNO₃, wrong	NH₂ and OH on one carbon, only 5 C	both wrong

4. So. X is NaOH and Y is 1-amino-3-methylpentan-2-ol, CH₃CH₂CH(CH₃)CH(OH)CH₂NH₂. That is option (c).

The idea to keep. Cyanohydrin formation needs a base to generate CN⁻. Reducing a cyanohydrin with LiAlH₄ gives a 1,2-amino alcohol that keeps the extra carbon from CN.

Answer from the NTA final answer key. Solution by PrepWiser.