Question

state the law of conservation of linear momentum and drive it from Newton's second law of motion

Answer 1

$\textbf{Answer is in Attachment !}$

Answer 2

Newton's second law of motion says that rate of change of linear momentum of a body is equal to the net external force applied on it. If the net external force acting on a body is zero, then the rate of change of momentum is also zero, which means that there is no change in momentum.