In which of the following reactions, hydrogen is one of the products? i. $\mathrm{NaBH}_4+\mathrm{I}_2 \longrightarrow$ ii. $\mathrm{BF}_3+\mathrm{NaH} \xrightarrow{450 \mathrm{~K}}$ iii. $\mathrm{BF}_3+\mathrm{LiAlH}_4 \longrightarrow$ iv. $\mathrm{B}_2 \mathrm{H}_6+\mathrm{NH}_3 \xrightarrow{\text { heat }}$

• A

  ii, iii
• B

  i, ii
• Correct answer
  C

  i, iv
• D

  iii, iv

Solution

(i) $2 \mathrm{NaBH}_4+\mathrm{I}_2 \longrightarrow \mathrm{~B}_2 \mathrm{H}_6+2 \mathrm{NaI}+\mathrm{H}_2$ (ii) $2 \mathrm{BF}_3+6 \mathrm{NaH} \xrightarrow{450 \mathrm{~K}} \mathrm{~B}_2 \mathrm{H}_6+6 \mathrm{NaF}$ (iii) $4 \mathrm{BF}_3+3 \mathrm{LiAlH}_4 \longrightarrow 2 \mathrm{~B}_2 \mathrm{H}_6+3 \mathrm{LiF}+3 \mathrm{AlF}_3$

So in reaction (i) and (iv) hydrogen is one of the product.

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