At what angle should a particle be projected to cover the maximum range (in $^{\circ}$)?

From the top of a tower $19.6 \,m$ high, a ball is thrown horizontally. If the line joining the point of projection to the point where it hits the ground makes an angle of $45^{\circ}$ with the horizontal, then the initial velocity of the ball is (in $\,m/s$)

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 $y = (8t - 5t^2) \ m$ and $x = 6t \ m$,where $t$ is in seconds. The velocity with which the projectile is projected is ......... $m/s$.

$A$ body is projected from the ground at an angle of $\tan^{-1}(\sqrt{7})$ with the horizontal. At half of the maximum height, the speed of the body is '$n$' times the speed of projection. The value of '$n$' is

For a body projected at an angle with the horizontal from the ground,choose the correct statement.

The maximum horizontal range of a projectile is $16 \ km$. When the projectile is thrown at an elevation of $30^o$ from the horizontal,it will reach a maximum height of ....... $km$.