An object is thrown vertically upwards. At its maximum height,which of the following quantities becomes zero?

$A$ stone dropped from the top of the tower touches the ground in $4 \, s$. The height of the tower is about..........$m$.

$A$ juggler tosses a ball up in the air with initial speed $u$. At the instant it reaches its maximum height $H$,he tosses up a second ball with the same initial speed. The two balls will collide at a height:

$A$ body is thrown vertically upwards with velocity $u$. The distance travelled by it in the fifth and the sixth seconds are equal. The velocity $u$ is given by.........$m/s$ $(g = 9.8\, m/s^{2})$

$A$ stone falls freely such that the distance covered by it in the last second of its motion is equal to the distance covered by it in the first $5 \,s$. It is in air for....... $s$.

$Assertion$: If a body is thrown upwards,the distance covered by it in the last second of upward motion is about $5 \ m$ irrespective of its initial speed.
$Reason$: The distance covered in the last second of upward motion is equal to that covered in the first second of downward motion when the particle is dropped.