An organic compound 'A' on reaction with NH₃ followed by heating gives compound B. Which on further strong heating gives compound C (C₈H₅NO₂). Compound C on sequential reaction with ethanolic KOH, alkyl chloride and hydrolysis with alkali gives a primary amine. The compound A is :

Solution

Chemistry ma’am · 4 steps

Read C₈H₅NO₂ with Gabriel steps as phthalimide, then work back to the acid that builds it.

1. Spot compound C. Ethanolic KOH, then an alkyl chloride, then alkaline hydrolysis to a primary amine is the Gabriel phthalimide synthesis. Phthalimide, C₆H₄(CO)₂NH, has the formula C₈H₅NO₂, which matches C.
2. Work backwards. An imide has two C=O groups joined through one N. To get it from NH₃ and heat, A needs two carboxylic acid groups side by side on the ring. That is phthalic acid, option (c).

   C₆H₄(COOH)₂ →(NH₃, Δ) C₆H₄(CONH₂)₂ →(strong Δ, -NH₃) C₆H₄(CO)₂NH

3. Gabriel step. KOH removes the acidic N–H to give potassium phthalimide. The anion attacks R-Cl to give N-alkylphthalimide, and alkaline hydrolysis releases R-NH₂.
4. So. A is phthalic acid, B is phthalamide, C is phthalimide. The answer is (c).

The idea to keep. Ethanolic KOH, then R–X, then hydrolysis to a pure primary amine means Gabriel synthesis, and that always starts from phthalimide, which comes from phthalic acid.

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