Underline the correct alterntaive:
a) when a conservative force does positivie work on a body, the potential energy of the body increase/decreases/remains unaltered.
work done by a body against friction always results in a loss of its kinetic /potential energy.
c) The rate of change of total momentum of a many-particle system is proportional to the external force/ sum of the internal forces on the system.
d) In an inelastic collision of two bodies, the quantities which do not change after the collision are the total kinetic energy/total linear momentum/total enregy of the system of two bodies.

Explanation

As the work done by a conservative force is equal to negative of potential energy . Hence , when positive work is done by the conservative force the potential energy of the body will decrease .
(b) As the work done by a body against friction is at the cost of its kinetic energy . Hence , kinetic energy of the body will decrease .
(c ) As the internal forces cannnoot change the net momentum of a system . Therefore , the rate of change of total momentum of many particle system is proportional to external forces .
(d) In an inelastic collision of tw bodies , total linear momentum and also total energy of the system of two bodies do not change and remain conserved .