What is so fragile that when you say its name, you break it?

When James was nine years old he hammered a nail into a tree to mark his height. Ten years later, James returned to see how much higher the nail was. If the tree grew by four inches each year, how much higher would the nail be?

Which word is the odd one out:

First Second Third Forth Fifth Sixth Seventh Eighth

A prisoner is in jail. There are two doors, one leads to freedom one leads to death. There is a guard at each door. One guard always tells the truth, the other always tells lies. The prisoner is allowed one question to either of the guards.

What is the question that will take him to freedom.?

A boy and a doctor was fishing.The boy is the doctor’s son but the doctor is not the boy’s father. Who is the doctor?