A ball is thrown upwards and it returns to ground describing a parabolic path. Which of the following remains constant

From the top of a tower of height $40\,m$, a ball is projected upwards with a speed of $20\,m / s$ at an angle of elevation of $30^{\circ}$. The ratio of the total time taken by the ball to hit the ground to its time of flight (time taken to come back to the same elevation) is (take $g=10\,m / s ^2$ )

Two projectiles $A$ and $B$ are thrown with the same speed such that $A$ makes angle $\theta$ with the horizontal and $B$ makes angle $\theta$ with the vertical, then

The equation of a projectile is $y =\sqrt{3} x -\frac{ gx ^2}{2}$ the angle of projection is

Two particles in same vertical plane are thrown to strike at same time. One from ground and other from height $h$ vertically above it. Ground particle is thrown obliquly and it achives a maximum height $H$. The second particle is thrown horizontally with same speed. What can be maximum $h$ so that two particles strike in air.

The maximum height attained by a projectile is increased by $10\,\%$ by increasing its speed of projection, without changing the angle of projection. The percentage increases in the horizontal range will be $...........\,\%$