Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

What has 13 hearts but no other organs?

Before the start of the car race, John and Jacob have the same amount of fuel in their car. With this fuel, John can drive for 4 hours while Jacob can drive five hours.
After a time they realize that the amount of fuel left in John's car is 1/4th of the fuel in Jacob's.

For how long they are racing?

What is full of holes but still holds water?

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

I am white when I am dirty, and black when I am clean. What am I?

Can you identify the famous TV character from the rebus below?

Prove that the below maths equation is true.

8 + 8 = 91