Identify 'A' in the following reaction :

The correct product 'A' is butane, represented by the structural formula:
CH₃-CH₂-CH₂-CH₃

Reaction Analysis:

1. Reactant: The starting material shown in the question is butanone (also known as ethyl methyl ketone), which has the structure:
CH₃-CO-CH₂-CH₃

2. Reagents: The reaction is conducted in two steps:
(i) Hydrazine ($N_2{H}_4$)
(ii) Potassium hydroxide (KOH) in the presence of ethylene glycol as a high-boiling solvent under heating conditions.

3. Reaction Name: This specific set of reagents is used to perform the Wolff-Kishner reduction.

4. Mechanism and Transformation:
During the Wolff-Kishner reduction, the carbonyl group ($C=O$) of aldehydes or ketones is selectively reduced to a methylene group ($C{H}_2$). The reaction proceeds via the formation of a hydrazone intermediate ($>C=N-N{H}_2$), which then undergoes base-promoted decomposition with the elimination of nitrogen gas ($N_2$):

${\mathrm{CH}}_3-\mathrm{CO}-{\mathrm{CH}}_2-{\mathrm{CH}}_3+N_2{H}_4\to {\mathrm{CH}}_3-C(=N-{\mathrm{NH}}_2)-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

${\mathrm{CH}}_3-C(=N-{\mathrm{NH}}_2)-{\mathrm{CH}}_2-{\mathrm{CH}}_3\stackrel{\mathrm{KOH}/\mathrm{ethylene\; glycol}/\Delta }{\to }{\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3+N_2$

Thus, the carbonyl carbon of butanone is reduced to form the corresponding alkane, which is butane.