Manganese dioxide on heating with concentrated hydrochloric acid gives a greenish yellow gas, X. With excess of ammonia $\mathrm{X}$ gives $\mathrm{Y}$ and $\mathrm{Z}$. $\mathrm{Y}$ and $\mathrm{Z}$ respectively are

• A

  $\mathrm{NH}_4 \mathrm{~F}, \mathrm{~N}_2$
• B

  $\mathrm{NH}_4 \mathrm{I}, \mathrm{NOCl}$
• C

  $\mathrm{NCl}_3, \mathrm{HOCl}$
• Correct answer
  D

  $\mathrm{NH}_4 \mathrm{Cl}, \mathrm{N}_2$

Hence, the correct answer is option: 'D'.