What work can one never finish?

A boy and his father are caught in a traffic accident, and the father dies. Immediately the boy is rushed to a hospital, suffering from injuries. But the attending surgeon at the hospital, upon seeing the boy, says 'I cannot operate. This boy is my son.' How is this situation explained?

I am not a bull but I have horns.
I am not an ass but I have a pack saddle.
Wherever I go, I leave silver behind me.

Who am I?

How can you throw a ball as hard as you can and have it come back to you even if it doesn't hit anything there is nothing attached to it and no one else catches or throws it.

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

The horse jumps over the king.
Strangely there is absolutely no scratch on him.

Can anyone explain, how is this possible?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

What runs around the whole yard without moving?

A solo dice game is played. In this game, upon each turn, a normal pair of dice is rolled and the score is calculated not by adding the numbers but multiplying them.

In a particular game, the score for the second roll is five more than what was achieved in the first roll. The score for the third roll is six less than what was completed in the second roll. The score for the fourth roll is eleven more than what was achieved in the third. The score for the fifth roll is eight less than what was completed in the fourth.

Can you calculate the score for each of the five throws?