What goes up but never comes down?

I make two people out of one. What am I?

What can go up a chimney down, but can’t go down a chimney up?

You can hear me, but you can't touch or see me.

What am I?

What brings you down but never up?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A woman lives in a Tall building thirty-six floors high and served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

What is the longest word in the dictionary?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?