I’m tall when I’m young, and I’m short when I’m old. What am I?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

What does does this rebus picture means ?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

During which month do people sleep the least?

Why is a river so rich ?

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.

A sundial has the fewest moving parts of any timepiece. Which has the most?

You have to put a letter on the following to make it a meaningful word. The only challenge is that you can't use 'E'.

S E Q U E N C _

What can you hold in your right hand, but never in your left hand?