which of the two deforming force or restoring force is responsible for elastic behaviour of a substance…
Deforming force :
The external force acting on a body on account of which its size or shape or both change is defined as the deforming force.
Restoring force :
The force which restores the size and shape of the body when deformation forces are\ removed is called restoring force. Deforming force and restoring force are not action reaction pair. Restoring force opposes the change in the size and shape of a body
Restoring force is responsible for the elastic behaviour of the substance because it is this force which tends to restore the original configuration of the body, whereas the deforming force applied on the body produces only the extension or compression in it.