In the reaction,
$P, Q$ and $R$ respectively are

• Correct answer
  A

  $\mathrm{NaNO}_2+$ dil. $\mathrm{HCl}, \mathrm{HBF}_4, \mathrm{Cu}+\mathrm{NaNO}_2$
• B

  $\mathrm{NaNO}_2+$ conc. $\mathrm{HCl}, \mathrm{F}_2, \mathrm{Cu}+\mathrm{NaNO}_3$
• C

  $\mathrm{NaNO}_2+$ dil. $\mathrm{HCl}, \mathrm{BF}_3, \mathrm{Cu}+\mathrm{NaNO}_2$
• D

  $\mathrm{NaNO}_2+$ dil. $\mathrm{HCl}, \mathrm{F}_2, \mathrm{Cu}+\mathrm{NaNO}_3$

Solution

Thus $P, Q$ and $R$ are $\mathrm{NaNO}_2+$ dil $\mathrm{HCl}, \mathrm{HBF}_4$, $\mathrm{Cu}+\mathrm{NaNO}_2$ respectively.

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