Good Riddles

Question: The doctor gives you three pills and tells you to take one every half hour. How long before you run out of pills?

Question: When I was 2 years old, my brother was half my age. Now I am 100 years old, how old is my brother?

Question: A lawyer has a brother who is a Catholic priest. The lawyer wants to be a priest as well but cannot. Why not?

Question: I'm a measurement of time.
But you'll find me on a map, not a clock.

What am I?

Question: what is yours but you can't actually hold ?