Logic riddles for teens with simple answers

You can see me in water, but I never get wet. What am I?

What always comes into a house through the keyhole?

Where can you find rivers with no water, cities with no buildings and forests with no trees?

What happens when you throw a blue rock into the yellow sea?

What has one head, one foot and four legs?

I eat other animals. I have a big mouth. I am green. I live in the water. Who am I?

Thirty white horses on a red hill. First they champ, Then they stamp, Then they stand still. Who are they?

When you have me, you feel like sharing me. But, if you do share me, you don't have me. What am i?

It can fill a room without occupying space. What is that?

What can go up a chimney down but not down a chimney up?