Write any two advantages of physical changes.

Give reasons for the following:

Expansion and contraction are maximum in gases.

Give reasons for the following:

Silver pieces of jewellery tarnish when exposed to air.

Give reasons for the following:

Apples and some other fruits turn brown when cut surface is exposed to air.

Name the type of changes that occur in the burning of a candle. Explain with reason.

Name the type of change that occur during digestion of food. Explain with reason.