Good Riddles

Question: The more i am present, the less you can see me. Who am i?

Question: Sam has two sons named Nathan and Daniel, Daniel is exactly 5 years older than Nathan and Daniel was born on February 29th 1996. How old is Nathan?

Question: There are 5 frogs, 1 die. How many left?

Question: If Teresa's daughter is my daughter's mother, then what am I to Teresa?

Question: What is so delicate that even mentioning it breaks it?