What happens when
a. Sodium metal is dropped in water?
b. Sodium metal is heated in free supply of air?
c. Sodium peroxide dissolves in water?

Explanation

(i) `H_(2)` gas is evolved which catches fire due to the exothermicity of the reaction .
`2 Na (s) + 2 H_(2)O (l) to 2 NaOH (aq) + H_(2) (g)`
(ii) `Na_(2)O_(2)` along with a small amount of `Na_(2)O` is formed .
`2 Na(s) + O_(2)(g) to 2 underset("(minor)") (2 Na_(2)O(s))`
`Na_(2)O(s) + (1)/(2) O_(2) (s) to underset("(major)")(Na_(2)O_(2)(s))`
(iii) `H_(2)O_(2)` is formed
`Na_(2)O_(2) (s) + 2H_(2)O (l) to 2 NaOH (aq) + H_(2)O_(2) (l)`