Reaction of $\mathrm{BeO}$ with ammonia and hydrogen fluoride gives $\text{'}\mathrm{A}\text{'}$ which on thermal decomposition gives ${\mathrm{BeF}}_2$ and ${\mathrm{NH}}_4\mathrm{F}$. What is $\text{'}\mathrm{A}\text{'}$ ?

• A

  ${\mathrm{H}}_3{\mathrm{NBeF}}_3$
• Correct answer
  B

  ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{BeF}}_4$

• C

  $\left({\mathrm{NH}}_4\right)\left({\mathrm{BeF}}_3\right)$

• D

  ${\left({\mathrm{NH}}_4\right)}_2\left({\mathrm{Be}}_2{\mathrm{F}}_6\right)$

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