Fun Riddles

Question: I can be dropped from the tallest of buildings and survive,but drop me from the smallest ship and I won't.What am I?

Question: How many letters are in the answer to this riddle?

Question: It takes ten men ten hours to build a certain wall. How long does it take five men to build the same wall?

Question: You put me in dry but then I get wet.
The longer I stay in, the stronger it will get.

What am I?

Question: Flora killed several thousands of people without mercy. Afterwords, Flora disappeared and was never seen again. Yet the police never pursued her.Why?