Explain how center of mass helps the system to move as well as rotate​

the center of mass is the point of rotation that provides the least resistance to rotation. In fact, the instantaneous center of rotation doesn't instantaneously shift to be at the center of mass of the object once the external forces stop acting on the object.

Explanation:

1 a

2 b

3 b

4 d

5 d

6 d

explanation:

conservation of mass

mass before something happens = mass afterwards