Match the items in Column-$I$ with those in Column-$II$.

Column-$I$	Column-$II$
$(1)$ Change in momentum	$(a)$ Force
$(2)$ Rate of change of momentum	$(b)$ Impulse

$A$ force of $50 \text{ dynes}$ acts on a body of mass $5 \text{ g}$ which is at rest for an interval of $3 \text{ seconds}$. The impulse is:

$N$ bullets,each of mass $m \, kg$,are fired with a velocity $v \, m/s$ at the rate of $n$ bullets per second upon a wall. The reaction force offered by the wall to the bullets is given by:

$A$ ball hits a vertical wall horizontally at $10 \ m/s$ and bounces back at $10 \ m/s$. Which of the following statements is correct?

In projectile motion,two particles of masses $m_1$ and $m_2$ have velocities $\vec{V}_1$ and $\vec{V}_2$ respectively at time $t=0$. Their velocities become $\vec{V}_1^{\prime}$ and $\vec{V}_2^{\prime}$ at time $2t$ while still moving in air. The value of $[(m_1 \vec{V}_1^{\prime} + m_2 \vec{V}_2^{\prime}) - (m_1 \vec{V}_1 + m_2 \vec{V}_2)]$ is ($g =$ acceleration due to gravity).

The position-time $(x-t)$ graph of a moving body of mass $2 \, kg$ is shown in the figure. The impulse on the body at $t=4 \, s$ is