Calorific Value

Q.

Define ignition temperature?

Q. Which of the following is not a component of a fire triangle?

1. Oxygen
2. Nitrogen
3. Fuel
4. Heat

Q. It is known that exposure to carbon monoxide is harmful to animals because:

1. It reduces $C{O}_2$ transport
2. It reduces $O_2$ transport
3. It increases $C{O}_2$ transport
4. It increases $O_2$ transport

Q.

Increase in the average temperature of Earth's climate is called ______________.

1. Global heating

2. Global warming

3. Earth heating

4. Natural heating

Q.

The usage of LPG in rural areas should be promoted because:

1. it burns easily.

2. it is easily available in the village.
3. it has high calorific value.

4. it is a clean fuel.

Q. Which of the following statements are true about the different regions of a candle flame?

1. Complete combustion takes place in the inner zone.
2. Partial combustion takes place in the middle zone.
3. Complete combustion takes place in the outer zone.
4. Partial combustion takes place in the outer zone.

Q. Arrange the different zones of a flame in increasing order of its temperature.

1. Middle zone< inner zone < outermost zone
2. Inner zone < middle zone < outermost zone
3. Inner zone < outermost zone< middle zone
4. Outermost zone < inner zone < middle zone

Q.

Assertion: Carbon dioxide is used in fire extinguishers.

Reason: Carbon dioxide is a colourless and odourless gas.

1. Both assertion and reason are true and the reason is the correct explanation for the assertion.

2. Both assertion and reason are true but the reason is not the correct explanation for the assertion.

3. The assertion is true but the reason is false.

4. The assertion is false but the reason is true.

Q. Which of the following is not an attribute of an ideal fuel?

1. Low calorific value
2. Cheap and easily available
3. Moderate rate of combustion
4. Safe storage

Q. During combustion of gaseous fuels, deficiency of air gives a ___ flame

1. sooty
2. blue
3. bright
4. dazzling white

Q. Partial combustion takes place in the middle region of a candle flame. The temperature of this region is ________.

1. lower than inner region
2. higher than inner region
3. lower than outer region
4. higher than outer region

Q. Carbon dioxide extinguisher helps extinguish fire by:

1. cutting the supply of oxygen.
2. reducing the heat of surroundings.
3. limiting the supply of fuel.
4. cutting the supply of nitrogen.

Q. Rashmi (on left side) and Aditi (on right side) placed metal rods in the different zones of a candle flame as shown in the image below.


Which of the following observations are correct about this activity?

1. Aditi's metal rod is hotter
2. Rashmi's metal rod is hotter
3. Aditi's and Rashmi's metal rods have same temperature
4. Aditi's and Rashmi's metal rods don't change temperature

Q. The fire will continue to burn as long as there is fuel and .

1. oxygen
2. carbon dioxide
3. nitrogen
4. sulphur

Q.

The lowest temperature at which a substance must be heated before it begins to burn is called its_________________.

Q. Calorific value is the amount of heat liberated during the combustion of 1 kg of a substance.

1. False
2. True

Q. Assertion: CNG is a better fuel than petrol.
Reason: The calorific value of CNG and petrol is 50000kJ/kg and 45000 kJ/kg respectively.

1. Assertion: Correct
   Reason: Correct
   Reason is the correct explanation of assertion
2. Assertion: Incorrect
   Reason: Correct
3. Assertion: Incorrect
   Reason: Incorrect
4. Assertion: Correct
   Reason: Incorrect
   Reason is not the correct explanation of assertion.

Q. Which of the following are the effects of global warming?

1. Melting of polar ice caps
2. Increase in energy consumption
3. Rise of sea level
4. Increase in average temperature of earth's atmosphere

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. The S.I. unit of calorific value is kJ/kg.

1. True
2. False

Q. Generally, an ideal fuel has a _______ calorific value.

1. moderate
2. zero
3. low
4. high

Q. On burning completely 2.5 kg of a fuel produces 87500 kJ of heat energy. The calorific value of the fuel is –

1. 35, 000 kg/kJ
2. 35, 000 kJ/kg
3. 35, 000 J/kg
4. 35, 000 g/J

Q. A given mass of fuel having a calorific value of 45, 000 kJ/kg, on burning, produces 67, 500 kJ of heat. The mass of the fuel used is:

1. 1.5 kg
2. 5 kg
3. 2 kg
4. 15 kg