A balloon when kept in sun, bursts after some time because:

i. As we know that on increasing the temperature, the kinetic energy of the gases increase.

ii. When the balloon is kept in the sun, due to sun’s heat (temperature increases), the kinetic energy of the gaseous particles also increases.

iii. As a result, the balloon expands and continues to expand in the sun’s heat.

iv. There comes a point when the balloon bursts.