Boron on reaction with fluorine forms $\mathbf{P}$, which on reaction with NaH at a high temperature produces $\mathbf{Q}$ along with a sodium salt. $\mathbf{P}$ on reaction with $\mathrm{NH}_3$ in $1: 1$ ratio gives $\mathbf{R}$. $\mathbf{Q}$ on reaction with $\mathrm{NH}_3$ in $1: 2$ ratio at an elevated temperature gives S . The correct statement is

• A

  $\mathrm{B}-\mathrm{N}$ bond in $\mathbf{R}$ is covalent in nature.
• B

  $\mathrm{All}$ $\mathrm{B}-\mathrm{H}$ bonds in $\mathbf{Q}$ are equivalent.
• C

  The shape of $\mathbf{S}$ is tetrahedral.
• Correct answer
  D

  Compound $\mathbf{Q}$ when dissolved in water gives an acid.

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