Fuels and Combustion

351.The gasification reaction represented by, C + H₂O = CO + H₂, is

1. Exothermic
2. Endothermic
3. Catalytic
4. Autocatalytic

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352.The heat of combustion of a fuel

1. Is equal to the heat of formation
2. Is always negative
3. Can't be known without calculating it
4. Is always positive

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353.The hottest part of the flame lies in its ___________ zone.

1. Non-luminous
2. Luminous
3. Yellow
4. Unburnt gases

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354.The internal energy of the combustion products is _________ compared to that of reactants.

1. More
2. Less
3. Equal
4. More or less; (depends on the state of fuel.)

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355.The liquid used for the washing of coal in an industrial coal washery is a mixture of water and

1. Carbon tetrachloride
2. Sand (40%)
3. Mineral oil of high viscosity & specific gravity (1.6)
4. None of these

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356.The lowest temperature, at which a solid fuel produces enough vapors to support continuous combustion, is called

1. Fire point
2. Smoke point
3. Burning temperature
4. Kindling temperature

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357.The main advantage of forced draft over natural draft is that

1. Combustion of fuel is complete
2. Smaller height chimney can be used
3. Furnace control is easier
4. All (A), (B) & (C)

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358.The main drawback of supplying more excess air in the combustion of fuel is the

1. Excessive power requirement of air blower
2. Enhanced sensible heat loss in the flue gas
3. Intermittent and uncontrolled combustion of the fuel
4. High exit flue gas temperature from the furnace

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359.The main function of primary air in pulverised coal fired burner is to

1. Burn CO to CO₂
2. Dry and transport the coal
3. Have proper combustion by supplying it around the burner
4. Preheat the tertiary air used for complete combustion of CO to CO₂

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360.The main product of high temperature carbonisation of coal is

1. Coke
2. Ammonia
3. Tar
4. Coke oven gas

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