Logic Riddles

Question: The more you add, the less it weighs.

Question: I'm simple for a few people But hard for them to hear I live inside of secrets I bring people's worst fears What am I?

Question: A horse jumps over a castle and lands on a man, then the man disappears. How was this possible?

Question: What gets broken without being held?

Question: People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?