Riddle #371

I’m the end of the colourful rainbow. What am I?

What am I?

While I am in air, I am not in oxygen. I am also in water, but not in hydrogen. I am necessary in all animals, but you won't find me in the zoo. Look in all brains and you'll find me there too. What am I?

Forward I am heavy, but backward I am not. What am I?

I am a seed with three letters in my name. Take away the last two and I still sound the same. What am I?

Elmer Johnson went to the hardware store to make a purchase for his house. He asked the store clerk, "How much will one cost?" The clerk thought for a moment and said, "Three dollars." Elmer Johnson, who looked a little puzzled said, "Well then, how much will twelve cost?" "Six dollars," replied the clerk. Elmer Johnson scratched his head and said, "If I were to purchase two hundred, how much would that cost?" "That," said the clerk, "will cost you nine dollars." What was Elmer Johnson buying?

I get whiter the dirtier I get. What am I?

A man was driving a black truck. His lights were not on. The moon was not out. A lady was crossing the street. How did the man see her?

I go around all the places, cities, towns and villages, but never come inside. What am I?

I am a home of knowledge, both banal and profound. In grand halls and small homes I can be found. I am a home for things of many leaves, but my many residents are not living trees. What am I?

Wash it and it isn't clean. Don't wash it and then it's clean. What I Am?