Question

In fusion reaction two light nuclie fuse together to form one heavy nucleus.. We know like charges repel each other then how it's possible for the nuclie to fuse 2gether.
2. How is energy released during fusion reaction.a

Answer 1

if the nuclei have sufficient kinetic energy (usually in the form of high temperature), they can overcome the electrostatic repulsion and approach each other to the distance where the attractive nuclear force (binding energy) takes hold

2. the mass of the fused nucleus is less than the sum of the masses of the constituent parts
this "mass defect" is converted to energy a-la Einstein ... E = mc^2