This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Calorific Value – 1”.
1. On which property of fuel it’s calorific value is based?
a) Specific heat
d) Ignition temperature
Explanation: The calorific value is the total amount of heat liberated by complete combustion a unit amount of fuel, which is the total efficiency of the fuel.
2. What is the unit of calorific value in fps(foot pound sec)?
a) Gram calorie (g cal)
b) Pound calorie
c) British thermal unit/ft3
Explanation: B.T.U. is the amount of heat required to rise the temperature of 1 lb of water through 1 0F. Centigrade heat unit (CHU) can also be used in fps system.
3. At how much temperature does the products of combustion should be cooled down to get Gross Calorific Value?
a) 288 K
b) 315 K
c) 390 K
d) 350 K
Explanation: At 288 K the products are cooled down, so as to get exact gross calorific value. It can be cooled down till room temperature.
4. What happens to the hydrogen present in fuel for calculating gross calorific value?
a) It combines with carbon to form methane
b) It combines with chlorine to form hydrochloric acid
c) It combines with oxygen to form hydrogen per oxide
d) It gets converted into steam
Explanation: After combustion of hydrogen, it gets converted into water vapour which then settles down as steam. After this process the products of combustion are cooled down.
5. How does the latent heat of condensation is included in gross calorific value?
a) By the steam produced by the combustion of hydrogen
b) By the combustion of products other than carbon and hydrogen
c) By the combustion of carbon
d) By the total heat produced in the system
Explanation: The steam generated after combustion gets condensed into water and latent heat is evolved. The latent heat so liberated is included in gross calorific value.
6. What’s the basic formulae for calculating gross calorific value?
a) [8080 %C + 3450(%H – %O∕8) + 2240 %S]∕100 cal/gm
b) [8080 %C + 34500(%H – %O∕24) + 2240 %S]∕100 cal/gm
c) [8080 %C + 34500(%H – %O∕16) + 2240 %S]∕100 cal/gm
d) [8080 %C + 34500(%H∕1 – %O∕8) + 2240 %S]∕100 cal/gm
Explanation: This formulae is also called as Dulong’s formula. With the help of %C,%H,%O and %S present in fuel gross calorific value can be calculated.
7. Net Calorific Value is greater than Gross Calorific Value.
Explanation: NCV = [GCV – 0.09%H×587] cal/gm, since both GCV and % H are positive the value of NCV will be less than GCV.
8. Which of the following properties a good fuel should have?
a) Low Calorific value
b) Moderate Calorific value
c) High Calorific value
d) High ignition temperature
Explanation: Calorific value is the total amount of heat liberated by complete combustion of fuel, therefore the more the calorific value will be, the good the fuel will be.
9. Which of the fuel has the highest calorific value?
d) Natural gas
Explanation: The calorific value of butane is 118 MJ/kg, this is due to the saturation of carbon bonding in butane, where as the calorific value of wood is lowest which is 16 MJ/kg.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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