You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

What kind of storm is always in a rush?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

A beggar on the street can make one cigarette out of every 6 cigarette butts he finds. After one whole day of searching and checking public ashtrays the beggar finds a total of 72 cigarette butts. How many cigarettes can he make and smoke from the butts he found?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

I don't get anymore wetter, no matter how much rain falls on me.

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

Name a key which is hardest to turn.