The compound(s) which react(s) with NH _ 3 to give boron nitride...

The compound(s) which react with ${NH}_{3}$ to form Boron nitride $\left(BN\right)$ is/are:

(A) Amorphous $B + {NH}_{3}\mathop{⟶}_{Tempreature}BN + {H}_{2}$

(B) ${B}_{2}{H}_{6} + \mathop{{NH}_{3}}_{\left(excess\right)}\overset{HighTemp .}{⟶}{\left(BN\right)}_{x}$

(C) ${B}_{2}{O}_{3} + 2{NH}_{3}\overset{900 ° C}{⟶}2BN + 3{H}_{2}O$

(D) ${HBF}_{4} + {NH}_{3} ⟶ \left[{NH}_{4}^{⊕}\right]\left[{BF}_{4}^{⊖}\right]$

Hence, (A,B,C) are correct