What goes up but never comes down?

What has one eye, but can’t see?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

Count the number of squares in the picture below.

A blonde put eyeliner on her head. Why?

Find the missing letter in the last circle logically in the given below picture.

What Deficiency does the below rebus represent?

VIT_MIN