what does this picture(rebus) riddle means ?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

A man wants to cross the pit of fire which is 25 feet in length and he has 2 planks(fire resistant) 19 feet in length. How can he cross the pit of fire alive?

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

A man was just doing his job when his suit was torn. Why did he die three minutes later?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

10+10 and 11+11 can give you the same answer.

Explain how?

One absent-minded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he travelled on foot to his friend's place a few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

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