Fill in the blanks using the words given in the box.

ignition, petrol, combustion, calorific value, combustible, inflammable

(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 __________.

Match the following for the flame of a candle.

If you hold a piece of iron wire with a pair of tongs inside a candle flame or a Bunsen burner flame, what will you observe? Will it produce a flame?

People usually keep Angethi/burning coal in their closed rooms during winter season. Why is it advised to keep the door open?

Write True/False against the following statements and also correct the false statement.

(a) A physical process in which a substance reacts with oxygen to give off heat is called combustion.

(b) Water is the best extinguisher for fires involving electrical equipment.

(c) Alcohol, CNG and LPG are inflammable substances.

(d) Increased concentration of nitrogen in air is believed to cause global warming.

(e) Greater the calorific value, better is the fuel.

(f) Middle zone is the hottest zone of a flame.

(g) The substances which vaporize during burning, give flame.