Page 125 - Science Class 6 Times Publication

Conclusion: The change in colour of lime water to milky colour is
due to carbon dioxide present in the air.

Water vapour

We dry wet clothes by keeping them in the sun shine. Similarly,
drying of lakes and ponds occurs in summer and winter season.
Here, water from the wet clothers, lakes and ponds evaporates and
moves towards the atmosphere. Thus, water vapour is present in
air. The water vapour gets condensed from the atmosphere due to low
temperature and falls to the earth surface in the form of rain. Fog and
mist are also the examples of water vapour. The amount of water
vapour present in the air is called humidity.

The water vapour present in the atmosphere prevents the drying out

of leaves of plants as well as fruits and owers. It protects the skin of
animals from drying.
Rusting

When you keep an iron nail in a moist place for some days, you will
notice the turning of the iron into reddish brown colour. It is called
rusting. It is due to the reaction of iron with oxygen in the presence
of water vapour and formation of iron oxide. This iron oxide is called
rust. Thus, the process of formation of rust by the slow oxidation of
iron in the presence of water vapour and oxygen is called rusting.

Activity 11.3

To prove that air contains water vapour

Materials required: A glass, ice cubes, etc.

Procedure
1. Take a glass and put some ice cubes in the

glass.
2. Leave it for 10 minutes. What will you
observe?

Times' Crucial Science and Environment 121 Book 6