Action-reaction forces act

State whether the following statement is true or false:
Impulse represents the rate of change of momentum of a body.

An athlete always runs some distance before taking a jump. Why?

$A$ bullet of mass $m$ is fired from a gun of mass $M$. If the velocity of the bullet is $v$,derive an expression for the recoil velocity of the gun. On which principle is this based?

An object experiences a net zero external unbalanced force. Is it possible for the object to be moving with a non-zero velocity? If yes,state the conditions that must be placed on the magnitude and direction of the velocity. If no,provide a reason.

The momentum of a body of given mass is proportional to its