What is black when you buy it, red when you use it, and gray when you throw it away?

What runs around the whole yard without moving?

You bought me for dinner but never eat me. What am I?

Which letter of the alphabet has the most water?

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?

On rolling two dices (six-sided normal dice) together, what is the probability that the first one comes up with a 2 and the second one comes up with a 5?

It belongs to you, but other people use it more than you do. What is it?

Name a key which is hardest to turn.

John buys rice at Rs.60/kg from Britain and then sells them at Rs.5/kg in India. As a result of this, he becomes a millionaire. How come?

Solve the rebus riddle in the picture below.