Solution:

Tank "F".

Explanation:
The water will flow as illustrated in the picture below and hence Tank "F" will fill first.
Note: Water supply for pipe "H" is blocked and hence won't fill at all.

Solution:

Ganpat had a black suit and a brown suit.
Harish had a brown suit and a pink suit.
Manoj had a white suit and a black suit.
Tarun had a pink suit and a white suit.

Solution:

Batsman hit six and gone retired hurt while the new batsman come to play and get runout for his wicket and the other batsman hit six and made both century and team win..

Solution:

Solution is shown in image below

Solution:

See the colored sticks in the picture. We have moved those sticks in the position given in the second image corresponding with the color.

Solution:

888 + 88 + 8 + 8 + 8 = 1000

Solution:

The clerk said that every day the password is CHANGED. Changed is the password.

Solution:

7 Races.

Solution:

It is not possible to guess only three fruits correctly: the fourth fruit is then correct too! So nobody has guessed three fruits correctly and 123-43-39-31 = 10 people have guessed four fruits correctly.

Solution:

We now have a square of 3x3 size, 2 squares of 2x2 size and 5 squares of 1x1 size.

Solution:

The Stars