Answer: Option A. -> True
:
A
Inertia is the natural tendency of an object to resist a change in its state of motion or of rest. Quantitatively, the inertia of an object is measured by its mass. More the mass more will be its inertia. As object A is heavier than object B, it has more inertia.

Answer: Option A. -> Opposite to the bullet's direction.
:
A
The total momentum of the bullet-pistol system was initially zero as both of them were at rest with respect to ground. During the shooting of the bullet, net external force on the gun and bullet system is zero. Hence, according to the law of conservation of momentum, the total momentum of the system will be zero even after firing the shot. Since the momentum of the bullet will be in forward direction, in order to balance it, the momentum of the pistol should be in backward direction or the pistol should move backwards.

Answer: Option B. -> move forward
:
B
When the tanker is in motion, the water inside will also be in motion. When the tanker comes to an abrupt stop, the water's inertia of motion resists this sudden change in motion. As a result, the water will move forward, before eventually coming to rest.

Answer: Option C. -> $4500N$
:
C

Here, mass m = $1500kg$
Initial velocity, u = 0, final velocity, v = $30m{s}^{-1}$, time taken, t = $10s$.
Now, putting these values in the first equation of motion,$v=u+at$, we get
$30=0+a\times t$,
$\Rightarrow$ $10a=30$
$\Rightarrow$ $a=3m{s}^{-2}$
Now, putting $m=1500kg$ and a = $3m{s}^{-2}$ in equation, $F=m\times a$, we get
$F=1500\times 3$ = $4500N$.
Thus, the force required is $4500N$.

Answer: Option A. -> True
:
A

According to Newton's third law, when a body $A$ exerts a force on another body $B$, $B$ also exerts an equal and opposite force on $A$. Hence, while kicking a ball, the footballer's leg will experience an equal amount of force but in opposite direction to that of the force he exerted on the ball.

Answer: Option A. -> $1.25s$
:
A

Let mass of cannon be $m_1$ = $400kg$
Let mass of cannon ball be $m_2$ = $2kg$
Let initial velocities of the cannon and cannon ball be $u_1$ and $u_2$ respectively.
Let final velocity of cannon and cannon ball be $v_1$ and $v_2$ respectively.
From the law of conservation of momentum,
total momentum before firing = total momentum after firing.
$\therefore$ $m_1{u}_1+m_2{u}_2=m_1{v}_1+m_2{v}_2$
As the cannon and cannon ball is at rest initially, the initial velocity will be zero, i.e 
$0=m_1{v}_1+m_2{v}_2$
Substituting the values: 
$0=400\times (-2)+2\times v$
$\Rightarrow v=\frac{400\times 2}{2}=400m{s}^{-1}$
Hence, the velocity of the cannonball will be $400m{s}^{-1}$​
Since we know,
$time=\frac{displacement}{velocity}$
Thus, time taken to hit the target= $\frac{500}{400}$ = $1.25s$

Answer: Option B. -> Unbalanced force
:
B

It is clear from the given information that Arun is pushing harder, i.e., their pushes are unequal. Hence, the net force between them will be unbalanced and the direction of force will be as shown in the given figure. 

Answer: Option A. -> Force
:
A
From, Newton's second law of motion, we know , $F=m\times a$ where $F$ is the force applied, $m$ is the mass and $a$ is the acceleration. The SI unit of mass is $kg$ and acceleration is $m{s}^{-2}$. So, the SI unit of force is $kgm{s}^{-2}$, also known as Newton(N).

Answer: Option D. -> $10kg$
:
D
Given, force, $F=30N$ and acceleration, $a=3{ms}^{-2}$.
Let m be the mass of the body.
We know, $F=ma$ (Newtons's second law of motion)
$\therefore$ $m=\frac{F}{a}=\frac{30}{3}=10kg$
Therefore, mass of the body is $10kg$.  

Answer: Option A. -> True
:
A

Initially, the total momentum was zero and after the man starts moving, the total momentum would still be zero as no external force is acting on the system of the man and the boat (law of conservation of momentum). So, the boat will move in the direction opposite to the direction of motion of the man.