Answer:
The velocity at which it hits the ground is 4.8497
.
Given:
Height of the ball = 1.2 meter
To find:
The velocity does it hit the ground = ?
Formula used:

Where v = final velocity of the ball
u = initial velocity of the ball
a = acceleration due to gravity = 9.8 
s = distance travelled by the ball = 1.2 meter
Solution:
A tennis ball is dropped from 1.20 m above the ground.
According to kinematic equation of motion,

Where v = final velocity of the ball
u = initial velocity of the ball = 0 
a = acceleration due to gravity = 9.8 
s = distance travelled by the ball = 1.2 meter
Thus,
= 0 + 2 × 9.8 × 1.2
= 23.52
v = 4.8497 
Hence, the velocity at which it hits the ground is 4.8497
.