1. Fill in the blanks in the following sentences.
(a) A ____________ process in which a substance reacts with __________ to give off heat is called combustion.
(b) When the clothes of a person catch __________, the person is covered with a __________ to extinguish fire.
(c) The __________ temperature at which a substance catches fire is called its __________ temperature.
(d) The substances which have very ________________ ignition temperature and can easily catch fire with a flame are called __________ substances.
(e) The substances which vapourise during __________, give flame.
2. Indicate whether the following statements are True or False. Also write the false statements in their correct form.
(a) Air is necessary for combustion.
(b) Magnesium is a non-combustible metal.
(c) Carbon dioxide is an excellent fire extinguisher.
(d) Calorific value of wood is higher than that of coal
3. Match the following for the flame of a candle.
| Column A | Column B Column C (zone) | Column C (colour) |
| (a) hottest part | (i) innermost zone | (x) the blue of unburnt wax vapours |
| (b) moderately hot | (ii) the middle zone of black partial combustion | (y) black |
| (c) least hot | (iii) the outer zone of complete combustion | (z) yellow |
(a) A chemical process in which a substance reacts with oxygen to give off heat is called __________.
(b) Wood, paper, CNG are __________ substances.
(c) The lowest temperature at which a substance catches fire is called its __________ temperature.
(d) Ignition temperature of __________ is lower than that of wood.
(e) The substances which have very low __________ temperature and can easily catch fire with a flame are called __________ substances.
(f) The amount of heat energy produced on complete combustion of 1kg of a fuel is called its __________
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