Question

if a large energy is required for nuclear fusion ... how does sun does it??

Answer 1

nuclear fusion happening on the surface of sun provides neccesary energy for nuclear fission.

Answer 2

hey mate....

here is ur answer..

The mass of the sun is so large that the pressure put on the atoms at it's core to get closer together is so strong that the atoms fuse. Nuclear fusionthat happens on the sun in which hydrogen converts to helium. Sun has so much hydrogen to continue the process for few more billion years.