Calorific Value and Efficiency of a Fuel

Q.

Combustion of a fuel is an exothermic reaction. True/False

1. True

2. False

Q.

Consider the following chemical equation for the combustion of methane ($C{H}_4$)

$C{H}_4+2O_2\to C{O}_2+2H_{2}O$

1. Energy required to break bonds between C and H in CH₄ is less than the energy required to form them.

2. Energy required to break bonds between C and H in CH₄ is more than the energy required to form them

3. Reactants have more energy than the products

4. Products have more energy than the reactants.

Q.

Among the following fuels, which has the least calorific value:

CNG, Petrol, Cow Dung Cake, Wood.

1. Cow Dung Cake

2. Wood

3. Petrol

4. CNG

Q. Which of the following will produce more heat?
1. $3kg$ of fuel X (Calorific value $=12000J/kg$)
2. $4kg$ of fuel Y (Calorific value $=10000J/kg$)

1. Fuel X
2. Fuel Y
3. Both will be equal
4. Insufficient information

Q. In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180, 000 kJ. Calculate the calorific value of the fuel.
[2 marks]
[NCERT Q.11]
[Calorific value]

Q.

"A fuel has calorific value of 25, 000 kJ/kg."
Which among the following options does the above statement implies to?

1. 4 kg of fuel will release 1, 00, 000 kJ of energy on complete combustion.
2. 1 kg of fuel will release 1, 00, 000 kJ of energy on complete combustion.
3. 1 kg of fuel will take in 25, 000 kJ of energy on complete combustion.
4. 4 kg of fuel will take in 1, 00, 000 kJ of energy on complete combustion.

Q. Total heat produced in combustion =

1. None of these
2. Calorific value x mass of substance combusted
3. Calorific value + mass of substance combusted
4. Calorific value/mass of substance combusted

Q.

Which of the following is correct with respect to calorific value?

1. It is the amount of heat energy produced on complete combustion of 1 kg of fuel.

2. It is the amount of heat energy produced on complete combustion of 1g of fuel.

3. It is the amount of heat energy required for complete combustion of 1 kg of fuel.

4. It is the amount of heat energy produced on complete combustion of 100 kg of fuel.

Q. A substance that has higher calorific value is usually a more economical fuel.

1. True
2. False

Q. Which among the following has the highest calorific value?

1. Wood
2. Petrol
3. Coal
4. Cowdung cake