The velocity of a particle moving in a straight line varies with time in such a manner that $v$ versus $t$ graph is velocity is $v_m$ and the total time of motion is $t_0$

(i) Average velocity of the particle is $\frac{\pi}{4} v_m$

(ii) Such motion cannot be realized in practical terms

Choose the correct option on the basis of above two statements.

The height $y$ and the distance $x$ along the horizontal plane of a projectile on a certain planet (with no surrounding atmosphere) are given by $y=8 t-5 t^2 \mathrm{~m}$ and $x=6 t \mathrm{~m}$, where $t$ is in seconds. The velocity with which the projectile is projected is

A ball is projected horizontally with a velocity of $5 \mathrm{~ms}^{-1}$ from the top of a building 19.6 m high. How long will the ball take to hit the ground?

The horizontal range of a projectile is $4 \sqrt{3}$ times of its maximum height. The angle of projection will be