Question

An amount of 1.00 g of a gaseous compound of boron and hydrogen occupies 0.820 litre at 1.00 atm and at $3^{\circ }C.$ The compound is ($R=0.0820L$ atm mol${}^{-1}{K}^{-1}$, Atomic weight: H = 1.0, B = 10.8)

• A. $B{H}_3$
• B. $B_4{H}_{10}$
• C. $B_2{H}_6$
• D. $B_3{H}_{12}$

Answer 1

The correct option is C $B_2{H}_6$

$PV=nRTPV=\frac{m}{M}RT\Rightarrow M=\frac{mRT}{PV}=\frac{1\times 0.082\times 276}{1\times 0.82}=27.6g$
27.6 g correspond to molar mass of $B_2{H}_6$
Hence correct option is c.