The angular momentum of the α−particles which are scattered through large angles by the heavier nuclei, is conserved because
The angular momentum of α particles is conserved because there is no external torque.
(b) Total energy of a system is always conserved, no matter what internal and external forces on the body are present.
(c) Work done in the motion of a body over a closed loop is zero for every force in nature.
(d) In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system.