It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E

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

You need to arrange three 7 and mathematical symbols to form number 1?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

A man desired to get into his work building, however he had forgotten his code.
However, he did recollect five pieces of information
* Fifth number + Third number = 14
* The fourth number is one more than the second number.
* The first number is one less than twice the second number.
* The second number and the third number equals 10.
* The sum of all five numbers is 30.

What is the code ?

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?

There were five men at church, and it started raining while they were outside. The four that ran still got wet, but the one that was still stayed completely dry. Why did he stay dry?

A man is found dead with a knife in his back When the investigation is done. A chair lays beside him and the forensic team finds moisture around the body.

If he committed suicide, how did he do it?

Andrew sees a very rare bird named "Ruppell's vulture". Soon Andrew was dead. Can you explain the mystery, Mr. Sherlock?