What does below chemistry rebus means?

What does this below rebus puzzle mean?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

You can see three almost identical images below. Can you spot the odd one out from them?

If you had an infinite supply of water and 5-quart and 3-quart pails, how would you measure exactly 4 quarts? What is the least number of steps you need?

Three people are in a room. Ronni looks at the Nile. The Nile looks at Senthil. Ronni is married but Senthil is not married. At any point, is a married person looking at an unmarried person? Yes, No or Cannot be determined.

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.