Class 8 Combustion-Flame

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Combustion and Flame

Multiple Choice Questions (MCQs)

  1. An example of spontaneous combustion is :

(a) respiration

(b) burning of yellow phosphorus

(c) the burning of magnesium

(d) rusting

  1. The gas used in cooking cylinders is :

(a) CNG

(b) LPG

(c) hydrogen

(d) petroleum

  1. The hottest part of the flame is :

(a) luminous zone

(b) central zone

(c) non-luminous zone

(d) none of these

  1. One of the followings is not a combustible substance. which one?

(a) alcohol

(b) asbestos

(c) hydrogen

(d) chaff

  1. The gas formed by incomplete combustion of carbon is :

(a) carbon monoxide

(b) carbon dioxide

(c) sulphur dioxide

(d) water vapour

  1. Acid rain can be caused by the burning of :

(a) hydrogen

(b) LPG

(c) CNG

(d) coal

  1. Which of the following fuels is expected to leave a residue upon burning?

(a) Coal

(b) Petrol

(c) LPG

(d) CNG

  1. Which of these will extinguish a fire?

(a) Removing the combustible substance

(b) Reducing the temperature of combustible substance below the ignition temperature

(c) Cutting off the air supply

(d) All of these.

  1. Water is used to extinguish the fire because of it:

(a) raises the ignition temperature of the burning substance

(b) lowers the ignition temperature of the burning substance

(c) cools the burning substance to a temperature below its ignition temperature

(d) conducts heat

  1. Which among the following fuels has the highest calorific value?

(a) CNG

(b) LPG

(c) Hydrogen

(d) Petroleum

  1. Which of the following is not derived from a fossil fuel?

(a) CNG

(b) LPG

(c) Biogas

(d) Petroleum

  1. Which of the following statement is not correct about carbon dioxide acting as a

fire extinguisher for electrical fires?

(a) It is heavier than air

(b) It is lighter than air

(c) It is not combustible

(d) It does not support combustion

  1. Which of the following fuels has the lowest calorific value?

(a) Kerosene

(b) Biogas

(c) CNG

(d) LPG

  1. A heap of green leaves is lying in one corner of a park. The green leaves in

the heap burn with difficulty because :

(a) They contain a tough material called cellulose.

(b) They contain a lot of water

(c) They contain a green pigment chlorophyll.

(d) They do not get sufficient oxygen for burning.


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