Question

Which of the following are chemical changes ?

1. decaying of wood
2. burning of wood
3. sawing of wood
4. hammering of nail into wood

Options

• (i) and (ii)

• (ii) and (iii)

• (iii) and (iv)

• (i) and (iv)

Answer 1

(i) and (ii)

The processes in statements (i) and (ii) are chemical changes because decaying and burning causes formation of new compounds; thus they are chemical reactions. The processes in statements (iii) and (iv) are physical changes where no new compounds are formed.