If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

Vin Diesel is pulling a theft and has planned to run away with all the cash kept in the safe. But the only way to open the safe is the 13 character password. He has a set of five clues given to him by a trustworthy source.

Exactly two of the below statements are false.
The password is contained within this sentence.
The password is not in this hint.
The password is within only one of these statements.
At least one of the above statements is a lie.

Solve the puzzle by telling what does below picture means.

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

Given below is simple addition with a defined pattern pattern:
7 + 7 = 2
8 + 8 = 4
8 + 5 = 1
6 + 9 = 3
10 + 11 = 9

Can you analyze the pattern and find out the answer for:

4 + 9 = ?

You need to pick one entry from pot A and one from pot B to have a perfect match. Can you do it?

If your uncle’s sister is not your aunt, what relation is she to you?

By using 'because' continuously three times, can you make an English statement ?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?