What Am I? Riddles

Forward I am heavy, backwards I am not. What am I?

Forwards I am heavy, but backwards I am not. What am I?

Forwards im heavy, backwards im not. What am I?

Found at the back of a book or in an abdomen. What am I?

Found at the back of the book. What am I?

Found in pizza but also the sky. You’ll know I’m around when I’m close by. What am I?

Four leaves I have. What am I?

From house to house I go, sometimes narrow, sometimes wide. And whether there’s rain or snow I always stay outside. What am I?

Full of dark, filled with everything Both on my skin they color With my pack, I am always Afraid of the cat. What am I?

Give me laughter and I’ll become the death of many, give me hell and I’ll be your protector. What Am I?

Go slow, I’m normal. Go fast, I disappear. With only a trail to prove I was even here. I have a pair of wings. But I don’t need them to fly. For that I have my “feet”. What am I?

Going forward and backwards is what I do all day. I come in all different shapes and sizes. I can be scary, and I can calm you down. What am I?

Guided, I am scraping along, leaving behind my snow­white dust against that which I am scraping, for when I am scraping, I must. What am i?

Half of the population uses me, and you lose me all the time. I’m small and yellow, black, brown or silver. You use me to hold things up. What am I?