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

I look at you, you look at me I raise my right, you raise your left. What am I?

A man died, leaving $10,000,000 for his widow, 5 sons and 4 daughters. Each daughter received an equal amount, each son received twice as much as a daughter, and the widow received three times as much as a son.

How much did the widow receive?

Arrange the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 above and below the division line in a manner that the thus formed fractions equal to 1/3.

(You can use one number only once)

Different lights make me strange by changing me into different sizes. What am I?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

Can you tell a 3D object that has just two surfaces?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Which of the following words don't belong in the group and why?
CORSET, COSTER, SECTOR, ESCORT, COURTS