Question

1. Assertion: The sum of the clockwise
moments is equal to the sum of the
anticlockwise moments.
Reason: The principle of conservation of
momentum is valid if the external force on
the system is zero.

Answer 1

Actually, the "Principle of Momentum" states that the resultant impulse is always equal with that of the momentum.

So, if we add the sum total of all the individual momentum, i.e. (momenta in plural), then the resultant will always add up to a value of zero.

This policy is described in physics in conservation of momentum.

So it is an inherent property and that is why the sum of clockwise moments will be equal to that of the anticlockwise moments so that the resultant becomes zero.