Question

Nine volumes of a gaseous mixture consisting of gaseous organic compound $A$ and just sufficient amount of oxygen required for complete combustion yielded on burning four volumes of $C{O}_2$, six volumes of water vapour, and two volumes of $N_2$, all volumes measured at the same temperature and pressure. If the compound contains $C$, $H$, and $N$ only, the molecular formula of the compound $A$ is:

• A. $C_2{H}_3{N}_2$
• B. $C_2{H}_6{N}_2$
• C. $C_3{H}_6{N}_2$
• D. $C_3{H}_{6}N$

Answer 1

The correct option is B $C_2{H}_6{N}_2$

$2C_x{H}_y{N}_z+7O_2\to 4C{O}_2+6H_{2}O+2N_2$
By using the Principal of Atom Conservation, we get
$2x=4;x=2$
$2y=12;y=6$
$2z=4;z=2$
Therefore, the molecular formula is $C_2{H}_6{N}_2$.