Solution:

Birbal wrote - "This time will pass soon."

When read in good time, you will feel sad. However, it is essential to keep the fact in the mind. Thus, do not be haughty and keep doing the good work for society.

When read in bad time, you will feel optimistic and get a morale boost that with your hard work you can change the situation.

Solution:

23

Explanation:
If you interchange the digits in the squares, you will see that all the resulting numbers are square of some number. Now square root all the thus formed numbers and add them together and you will have the required number in the circle.

In the third figure:
61 = 16 and square root = 4
90 = 09 and square root = 3
18 = 81 and square root = 9
94 = 49 and square root = 7

4 + 3 + 9 + 7 = 23.

Solution:

This is because the contestants had to hold their breath.

Solution:

Mixing business with pleasure.(PbLuEsAiSnUeRsEs)

Solution:

22 + 2 = 24

Solution:

181

Explanation:
+11 =>16
+33 =>49
+55 =>104
+77 =>181

Solution:

If you see the picture, they formed a pentagonal shape and achieved the required.

Solution:

L, A and E are the missing letters which forms the word EVALUATE when read clockwise.

Solution:

If nobody goes there, then that restaurant can't be crowded.

Solution:

Chair is the required five letter word.