Question

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.​

Answer 1

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

• During combustion, oxygen in the atmosphere combines with the substances to produce heat, light and gases like $\left(C{O}_2\right)$.

Substance $+O_2\to \text{Heat + Light + Gases}\left(C{O}_2\right)$

(b) When the clothes of a person catch fire, the person is covered with a blanket to extinguish fire.​

• If a person's clothes catch fire, the best way to extinguish the fire is to cover the person with a woolen blanket. By covering with a blanket, the supply of oxygen (supporter of combustion) will be stopped.​
  

(c) The lowest temperature at which a substance catches fire is called its ignition temperature.​

• When exposed to air the substance easily catches fire at the ignition temperature.​

(d) The substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances.​

• When exposed to air inflammable substance easily catches fire at very low temperature.​

(d) The substances which vapourise during burning, give flame.​

• Flame producing substances are volatile compounds and vapourise to produce flame during combustion.​