What does below rebus means ?

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

Which part of London exists in France as well ?

Can you start the fire using two pieces of wood?

What is 3/7 chicken, 2/3 cat and 2/4 goat?

What does Alexander the Great and Winnie the Pooh have in common?

What does an Island and the letter T have in common?

I am quite hot but become too cold if you remove the first two letters. What am I?

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

Why do people go to bed?