Question

A balloon when kept in sun bursts after sometime why

Answer 1

Explanation:

The balloon will burst after kept under the heat of the sun for a while because heat expands  - and when the the gases inside the balloon start to heat up as result of a direct contact with the sun - it will burst as the balloon cannot hold so much expanding air.

Answer 2

A balloon when kept in sun bursts after some time because outside the temperature is high and due to that the kinetic energy increases and the molecules of gas particles inside exerts a pressure on the walls of the balloon so it will continue to expand and there a stage will come that the balloon will burst.