Give the structures of A, B and C in the following reaction :
`CH_(3)Br overset(KCN)(rarr) A overset(LiAlH_(4))(rarr) B underset(273 K)overset(HNO_(2))(rarr) C`.

Explanation

To solve the given reaction step-by-step, we will identify the structures of compounds A, B, and C.

### Step 1: Identify the starting compound
The starting compound is **CH₃Br**, which is methyl bromide.

### Step 2: Reaction with KCN
When methyl bromide (CH₃Br) reacts with potassium cyanide (KCN), the cyanide ion (CN⁻) acts as a nucleophile and attacks the carbon atom in CH₃Br. This results in the substitution of the bromine atom with the cyanide group. The reaction can be represented as follows:

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