Give an example of an elastic and an inelastic collision: ; state whether or not momentum and kinetic energy are conserved in each case.

Elastic collision is that collision in which two objects are collides and separate out without and deformation in shape and size

example: if a block connected with ideal spring will collide with another block in which spring will compress during the collision and then again come to its natural state.

Inelastic collision in that in which two objects will collide and then stick with each other after collision and there is permanent deformation in the objects.

example : if two cars will collide and stuck together after collision and move together with same speed

So here in both examples and both type of collision there is no external force during collision of two objects so here total momentum of the system will remains conserved.

But since the shape will change in inelastic collision so kinetic energy is not conserved in inelastic collision while in elastic collision kinetic energy is conserved

thermal energy is the answer