Good Riddles

Question: I break down buildings I crumble mountains You can't see me What am I?

Question: What goes up and down but never moves?

Question: I am important at the most dangerous times. I can not be seen, heard, or smelled. If you use me too much you would fatally die. What am I?

Question: Crawls over pages and fells wild beasts.
Helps guide you along in your home and on streets.

What is it?

Question: On a boat in a lake, there is a rope ladder. The rope ladder is 5 inches off the water. Then one day the lake waters rise 5 inches. How high off the water is the ladder now?