$ \Rightarrow \;\;t = \sqrt {\frac{{2 \times 5}}{{10}}} $$ = 1\;\sec $

As the water drops fall at regular intervals from a tap therefore time difference between any two drops $ = \frac{1}{2}\;\sec $

In this given time, distance of second drop from the tap

$ = \frac{1}{2}g{\left( {\frac{1}{2}} \right)^2} = \frac{5}{4} = 1.25\,m$

Its distance from the ground $ = 5 - 1.25 = 3.75\;m$