KVPY 2020-21 SB SX Exam Previous Papers

Question : 110 of 120

Marks: +1, -0

Sodium borohydride upon treatment with iodine produces a Lewis acid (X), which on heating with ammonia produces a cyclic compound (Y) and a colorless gas (Z). X, Y and Z are :

$X = BH_3 ; Y = BH_3 . NH_3 ; Z = N_2$
$X = B_2H_6 ; Y = B_3N_3H_6 ; Z = H_2$
$X = B_2H_6 ; Y = B_6H_6 ; Z = H_2$
$X = B_2H_6 ; Y = B_3N_3H_6 ; Z = N_2$

Validate

Solution:

2 {Na}[{BH}_{4}]+{I}_{2} {───▶}{B}_{2} {H}_{6}({X})+2 {NaI}+{H}_{2}

3 {B}_{2} {H}_{6}+6 {NH}_{3}{────▶} ↖{\Δ} 2 {B}_{3}{N}_{3} {H}_{6}({Y})

+12 {H}_{2}({Z})

{X}={B}_{2} {H}_{6}

{Y}={B}_{3} {N}_{3} {H}_{6}

{Z}=12 {H}_{2}

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