Q45 / 180 · AIIMS 2019 (25 May) · Chemistry

Compound ' $X$ ' on reduction with $\mathrm{LiAlH}_4$ gives a hydride ' $Y$ ' containing $21.72 \%$ hydrogen along with other products. The compound ' $Y$ ' reacts with air explosively to give $\mathrm{B}_2 \mathrm{O}_3 \cdot{ }^{\prime} X$ ' and ' $Y$ ' are respectively

  • A
    $\mathrm{B}_2 \mathrm{H}_6, \mathrm{BCl}_3$
  • Correct answer
    B
    $\mathrm{BCl}_3, \mathrm{~B}_2 \mathrm{H}_6$
  • C
    $\mathrm{AlCl}_3, \mathrm{AlH}_4^{-}$
  • D
    $\mathrm{BCl}_3, \mathrm{~B}_4 \mathrm{H}_{10}$

Solution

$\begin{aligned} & \text { } 4 \mathrm{BCl}_3+3 \mathrm{LiAlH}_4 \underset{Y}{\stackrel{\text { Ether }}{\longrightarrow}} \underset{Y}{2 \mathrm{~B}_2 \mathrm{H}_6}+3 \mathrm{AlCl}_3 \\ & +3 \mathrm{LiCl} \\ & \% \text { of } \mathrm{H} \text { in } \mathrm{B}_2 \mathrm{H}_6=(6 / 27.62) \times 100=21.72 \\ & \mathrm{~B}_2 \mathrm{H}_6+3 \mathrm{O}_2 \text { (air) } \stackrel{\text { Explosion }}{\longrightarrow} \mathrm{B}_2 \mathrm{O}_3+3 \mathrm{H}_2 \mathrm{O} \\ & \text { Y } \\ & \end{aligned}$

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

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