Best riddles

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

What is invisible and makes people suffer from symptoms like sweating and nausea, yet people can’t survive without it?

Mike was watching T.V. and all of a sudden he leaps to his feet and says, "That's Simon", pointing at someone who was at the screen. Then his brother Mark comes in, looks at his brother, then looks back at the T.V. and says, "So it is." How do they know Simon if they hadn't seen him before, no pictures, nothing?

A 400 yard long train, travelling at 30 mph, enters a 4.5 mile long tunnel. How long will elapse between the moment the front of the train enters the tunnel and the moment the end of the train clears the tunnel?

There is a low railroad bridge in your town. One day you see a large truck stopped just before the underpass. When you ask what has happened, the driver tells you that his truck is one inch higher than the indicated height of the opening. This is the only road to his destination. What can he do to get through the underpass the easiest way?

What is it that you throw away the outer side, then cook the insides and then throw away the insides – what is the name of the item?

I am in a land where thirty men and two women were dressed in classic black and white dress. They began to fight as soon as any of them moves. Where am I ?

I'm in you, But not in him, I go up, But not down, I'm in the colosseum, But not a tower, I'm in a puzzle, But not a riddle.

I have just one, but with eight to spare, I am usually friendly, but I sometimes act like I don't care. What am I?

This is as light as a feather, yet no man can hold it for long. What am I?