This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What does below chemistry rebus means?

Find the missing number in the image below.

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

What Adam and Eve do not have but the rest of the people have?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?