Ans. 1 is 3 s..

since in both cases its dropped from rest, u =0

use s = 0.5*g*t² to get the total distance(ie take time as 5s)

Then find distance travelled in 4s(using same equatioon, time as 4 s)

Find distance yet to be covered by subtracting..

Again use s = 0.5 g*t² to get time.