1. Soln:
(a) A Chemical process in which a substance reacts with oxygen to give off heat is called combustion.
(b) When the clothes of a person catch fire, the person is covered with a blanket to extinguish the fire.
(c) The lowest temperature at which a substance catches fire is called its ignition temperature.
(d) The substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances.
(e) The substances which vapourise during burning give flame.
2. Soln:
- True
- False. Because, Magnesium is a combustible metal.
- True
- False- Because the alorific value of coal is higher than that of wood.
| Column A | Column B Column C (zone) | Column C (colour) |
| (a) hottest part | (iii) the outer zone of complete combustion | (x) the blue of unburnt wax vapours |
| (b) moderately hot | (ii) middle zone of black partial combustion | (z) yellow |
| (c) least hot | (i) innermost zone | (y) black |
(a) A chemical process in which a substance reacts with oxygen to give off heat is called combustion.
(b) Wood, paper, CNG are combustible substances.
(c) The lowest temperature at which a substance catches fire is called its Ignition temperature.
(d) Ignition temperature of petrol is lower than that of wood.
(e) The substances which have very low Ignition temperature and can easily catch fire with a flame are called Inflammable substances.
(f) The amount of heat energy produced on complete combustion of 1kg of a fuel is called its Calorific value.
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