Question

Give an example each of a change that involves:
(a) A change in colour
(b) Evolution of a gas
(c) Production of sound

Answer 1

a) Rusting of iron involves a colour change. On leaving a piece of iron in air, a chemical change takes place and a reddish-brown flaky layer is formed on its surface which is called rust.
b) When baking soda and vinegar are mixed, a chemical change takes place and carbon dioxide gas is releaed in the form of bubbles.
c) Explosion of fireworks is a chemical change which produces heat, light, sound, and also releases unpleasant gases.