Question

The order of the calorific values of fuel gases is:
(A) Carburetted water gas>Producer gas>Semi water gas
(B) Carburetted water gas> Semi water gas>Producer gas
(C) Producer gas> Semi water gas> Carburetted water gas
(D) Semi water gas>Producer gas> Carburetted water gas

Answer 1

Hint: The calorific value of a fuel refers to the amount of heat energy present in the fuel. This can be determined by the complete combustion of specified quantity of the fuel at constant pressure under normal conditions. The calorific value is also known as calorific power. Combustion is a high temperature exothermic chemical reaction involving a hydrocarbon or organic molecule reacting with oxygen to give carbon dioxide, water and evolution of heat.

Complete step by step answer:
We need to find out the order of the calorific values of the given fuel gases which are carburetted water gas, producer gas and semi water gas.
The composition of carburetted water gas is carbon monoxide, hydrogen and saturated and unsaturated hydrocarbons. Semi water gas is composed of carbon monoxide, hydrogen and nitrogen. Producer gas is composed of carbon monoxide and nitrogen.
The calorific values of any substance can be determined roughly by their chemical composition.
In carburetted water gas, all the constituents carbon monoxide, hydrogen and saturated and unsaturated hydrocarbons are combustible. So, the fraction of combustible constituents is 1.
Similarly, in semi water gas, except nitrogen all are combustible and hence the fraction of combustible constituents is two-third of the total constituents. And in producer gas, only carbon monoxide is combustible and hence the fraction of combustible constituents is one-halved of the total constituents.

So, the fraction of combustible gases and hence the calorific values will follow the order:
carburetted water gas> semi water gas >producer gas. Hence, the correct option is B.

Note: The knowledge of calorific values of fuels and foods are very necessary in our daily life. The gas suppliers use this information to bill the gas consumers. The human body also requires a specific amount of calories in diet. Too high or too low calorie consumption can lead to severe health problems.