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

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

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

How is a fly different from a mosquito?

John has eleven friends. He has a bowl containing eleven apples. Now He wants to divide the eleven apples among his friends, in such a way that an apple should remain in his bowl.
How can He do it?

Why Aeroplane windows are round?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

Suppose you are sitting in an interview and the interviewee asks you an aptitude question.

You have three buckets with a capacity of 4 litres, 8 litres and 10 litres and you have a large tank of water. Now you have to measure 3 litres of water precisely using those buckets. How will you do it?