John speaks the truth only once a day in a week. Below are a few hints for you:

First: Days are Sunday, Monday and so on.
Second: One day he says, "I lie on Monday and Tuesday".
Third: On the next day, he says, "Today is either Thursday, Saturday or Sunday".
Fourth: On the next day, he says, "I lie on Wednesday and Friday".

Can you identify the day on which he speaks the truth?

What breaks yet never falls, and what falls yet never breaks?

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

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

What is always in front of you but can’t be seen?

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

What seven-letter word has hundreds of letters in it?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

What goes through cities and fields, but never moves?