Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

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

John bought 150 chocolates but he misplaced some of them. His Father asked him how many chocolates were misplaced.
He gave the following answer to him:
If you count in pairs, one remains
If you count in threes, two remain
If you count in fours, three remain
If you count in fives, four remain
If you count in sixes, five remain
If you count in sevens, no chocolate remains.

Can you analyze the statements and tell us how many chocolates were lost?

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

No matter how little or how much you use me, you change me every month. What am I?

They are three errirs in this question. Can you find them?

A man wants to cross the pit of fire which is 25 feet in length and he has 2 planks(fire resistant) 19 feet in length. How can he cross the pit of fire alive?

There is a unique number which when multiplied by any number from 1 to 6, we will get the new number that contains the same digits only.

Can you find that number?

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

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?