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

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

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.

In the image below, can you find the value of an angle(y)

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

Suppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea.

Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?

What do you see in the given picture?

On the dull night when the blonde was dozing, she heard an odd clamour and she saw that there was a bizarre man with a gun simply outside her home. So she raced to the telephone to call the police, however, she can't dial 911. Why?

I have branches, but no fruit, trunk or leaves. What am I?