Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

What is wrong in the below Picture?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

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?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

John can fit six large chocolate boxes or nine small chocolate boxes into a carton. How many cartons will he require to put sixty-six chocolate boxes into?

A man desired to get into his work building, however he had forgotten his code.
However, he did recollect five pieces of information
* Fifth number + Third number = 14
* The fourth number is one more than the second number.
* The first number is one less than twice the second number.
* The second number and the third number equals 10.
* The sum of all five numbers is 30.

What is the code ?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?