The resultant of action and reaction is zero. (True or False)

$A$ ball of mass $50 \,g$ is dropped from a height of $20 \,m$. $A$ boy on the ground hits the ball vertically upwards with a bat with an average force of $200 \,N$,so that it attains a vertical height of $45 \,m$. The time for which the ball remains in contact with the bat is ........... of a second. [Take $g = 10 \,m/s^2$]

$A$ batsman hits back a ball of mass $0.4 \; kg$ straight in the direction of the bowler without changing its initial speed of $15 \; ms^{-1}$. The impulse imparted to the ball is $\dots \; Ns$.

$A$ solid horizontal surface is covered with a thin layer of oil. $A$ rectangular block of mass $m = 0.4 \ kg$ is at rest on this surface. An impulse of $1.0 \ N \ s$ is applied to the block at time $t = 0$ so that it starts moving along the $x$-axis with a velocity $v(t) = v_0 e^{-t/\tau}$,where $v_0$ is a constant and $\tau = 4 \ s$. The displacement of the block,in metres,at $t = \tau$ is. . . . . . . Take $e^{-1} = 0.37$.

In two different experiments,an object of mass $5 \; kg$ moving with a speed of $25 \; ms^{-1}$ hits two different walls and comes to rest within
$(i)$ $3 \; s$,$(ii)$ $5 \; s$,respectively.
Choose the correct option out of the following:

$A$ uniformly moving cricket ball is turned back by hitting it with a bat for a very short time interval. Show the variation of its acceleration with time (Take acceleration in the backward direction as positive).