Question 11 : Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
1. friability & oxygen content.
2. caking index.
3. yield of carbonised products.
4. calorific value.
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Question 12 : Combustion reaction of fuels is a/an __________ reaction.
1. exothermic
2. auto catalytic
3. none of these
4. endothermic
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Question 13 : Which of the following is not used as a binder in coal briquetting ?
1. Molasses
2. Pitch
3. Line
4. Tar
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Question 14 : Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.
1. oxygen
2. hydrogen
3. carbon
4. sulphur
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Question 15 : Size of blast furnace grade coke is __________ mm.
1. 25-80
2. >100
3. 0-15
4. 15-25
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Question 16 : The internal energy of the combustion products is __________ compared to that of reactants.
1. more
2. less
3. same
4. more or less ; (depends on the state of fuel.)
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Question 17 : During combustion of gaseous fuels, deficiency of air
1. increases the flame temperature.
2. does not affect the flame length.
3. lengthens the flame.
4. tends to shorten the flame.
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Question 18 : Higher efficiency in the combustion of solid fuel can not be achieved by
1. supplying correct quantity of combustion air.
2. adopting efficient-fuel firing technique & equipment.
3. proper fuel preparation.
4. keeping the flue gas exhaust temperature very high.
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Question 19 : Low temperature carbonisation
1. is mainly for producing the smokeless domestic coke.
2. produces higher quantity of gas than high temperature carbonisation.
3. is meant for the production of 'metallurgical coke'.
4. produces less quantity of tar than high temperature carbonisation.
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Question 20 : Gross and net calorific value of a fuel will be the same
1. ifits carbon content is very low.
2. under no circumstances.
3. if its hydrogen/hydrogen compound content is zero.
4. if its ash content is zero.
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