A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2. It means that___________________?

A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2. It means that___________________?

A. 21% excess air has been used for combustion
B. 21% excess oxygen has been used for combustion
C. Complete combustion of fuel has taken place
D. No excess air has been used for combustion

With increase in the temperature of carbonisation of coal ___________________?

With increase in the temperature of carbonisation of coal ___________________?

A. Hydrogen content of coke oven gas increases due to cracking of hydrocarbons
B. Methane content in the coke oven gas decreases and carbon monoxide content increases
C. Calorific value of the coke oven gas decreases due to cracking of hydrocarbons which is not
compensated by increase in CO & H2 content
D. All A., B. and C.