Which of the following are chemical changes? (i) Decaying of wood (ii) Burning of wood (iii) Sawing of wood (iv) Hammering of a nail into a piece of wood (a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (i) and (iv)

• Solution:

The answer is (a) (i) and (ii)

Explanation

Decaying of wood and burning of wood, because there will be a change of chemical composition and wood cannot be restored to its original form.

Sawing of wood and hammering of nails into a piece of wood are physical processes where the chemical composition of compounds is not changed.