Brain teasers

What goes down but never gets up?

What goes up and down but still remains in the same place?

John's father has  5 sons named ten, twenty, thirty, forty. What would e the name of the fifth?

What disappears the moment you say the name?

What word in the English language is always spelled incorrectly?

What number is closest to 600?    623 or 581 ?

What goes up but never goes down?

She lives in a one storey house. Walls and furniture are pink. What colour are the stairs ?

What has a mouth but cannot talk and runs but cannot walk?

What has a head and tail but no body?