The correct functional group $X$ and the reagent/reaction conditions $Y$ in the following schemes are $\mathrm{X}-\left(\mathrm{CH}_2\right)_4-X$

• A

  $X=\mathrm{COOCH}_3, Y=\mathrm{H}_2 / \mathrm{Ni} /$ heat
• B

  $X=\mathrm{CONH}_2, Y=\mathrm{H}_2 / \mathrm{Ni} /$ heat
• Correct answer
  C

  $X=\mathrm{CONH}_2, \quad Y=\mathrm{Br}_2 / \mathrm{NaOH}$
• Correct answer
  D

  $X=\mathrm{CN}, Y=\mathrm{H}_2 / \mathrm{Ni} /$ heat

Solution

(a)
(b)
(c)
(d)
$$ \text { In author's opinion (a) and (b) should also be the answer. } $$
Polyester, a condensation polymer

Hence, the correct answer is options: 'C', 'D'.