Define Physical change and chemical change. State which type of change occur in each of the following statemenet:

(a) Passing an electric current through molten magnesium chloride yields moltenm magnesium and gaseous chlorine.

(b) The iron in discarded automobiles slowly forms reddish brown, crumbly rust.

Answer: Physical change: It is reversible process and we can get back to orginal material. Best example is the interconversion of ice into water which inturn into vapour.

Chemical changes are irreversible and we can't get back the original material. Example combustion of coal, rusting of iron

Explanation:

1. Electrolysis of molten MgCl2 is chemical change since we can't get back MgCl2 after Electrolysis and new materials are formed.

2. It is an example rusting of iron comes under chemical changes.