volume = l x w x h
volume = 20 x 35 x 50 = 35,000 cubic cm
1 cubic cm = 0.001 liter
35000 x 0.001 = 35 liters of water is needed
The y-coordinate is between -1 and -2. It is close to halfway between -1 and -2, but it is a little less than halfway.
Answer: Choice B. 
Factoring, you have
h(t) = -16(t^2 -2 -8) = -16(t -4)(t +2)
The ball hits the ground when h(t) = 0, so
0 = -16(t -4)(t +2)
t = 4 or -2
The positive solution is the one of interest.
It will take 4 seconds for the ball to hit the ground.