Question

Heat of combustion of $CH_{4},C_{2}H_{6},C_{2}H_{4}$ and $C_{2}H_{2}$ gases are $-212.8,-373.0,-337.0$ and $-310.5Kcalmol^{- 1}$ respectively at the same temperature. The worst fuel among these gases is :-

• A. $CH_{4}$
• B. $C_{2}H_{6}$
• C. $C_{2}H_{4}$
• D. $C_{2}H_{2}$

Answer 1

Answer: (D)

Calorific value of $CH_{4}=\frac{+ 212 . 8}{16}=13.3cal$
Calorific value of $C_{2}H_{6}=\frac{373}{30}=12.43cal$
Calorific value of $C_{2}H_{4}=\frac{337}{28}=12.03cal$
Calorific value of $C_{2}H_{2}=\frac{310 . 5}{26}=11.94cal$
$C_{2}H_{2}$ has least calorific value hence worst fuel