Good Riddles

Question: A man is doing some work on his home and goes to a hardware store. He goes up to the clerk and tells him what he wants. The clerk tells him that each one is $1. He tells the clerk he would like 5000 and he is charged only $4.

What did he buy?

Question: What temperature is twice as hot as 0 degrees Celsius?

Question: A swan is in the center of a circular lake but he cannot take flight from the water, only on land. On the parameter of the lake there is a hunting dog that desperately wants the swan but cannot swim. So the swan must make it to the land before taking off and must do so before the dog makes it to him. The dog is almost 4 times faster than the swan and always runs to the point around the lake closest to the swan.

How can the swan get out of the lake and take flight before the dog gets him?

Question: Not chest or box is now discussed. Money can be held in it, but just as we test its metal, within it there is rust.

[What is it?]

Question: A man challenges the greatest chess player in the world to two games of chess. He guarantees that he will win or tie at least one of the games for sure. To be even more cocky, the man says he will play both games at the same time.

How does he guarantee he wins or ties at least one game?