What does below chemistry rebus means?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

If a boy blows 18 bubbles,
Then pops 6 eats 7 and then
He pops 5 and blows 1.
How many are left?

This is a simple one. You just have to count the number of Fs in the given sentence.

Finished Files are the result of years of scientific study combined with the experience of years.

How many did you count?

Solve the following series:
AZ, GT, MN, __, YB

On a certain day, John celebrated his birthday. Two days later, his older twin brother Jacob celebrated his birthday.

Is this even possible? How can it be?

One day, Birbal got late for a function and Akbar was highly disappointed.
Please forgive me Jahanpanah. I arrived late because my child was crying and I had to calm him down, explained Birbal.
Does it take this long to placate a child? questioned the emperor. I feel that you have no idea about how to raise a child. I order you to act like a child and I will act like your father to show you how you should have dealt with your child. Come on! Ask me all that he asked from you.
Father, I want a cow, said Birbal.
The emperor quickly ordered one of the servants to bring a cow to the kingdom.
I want to drink its milk, now, now, now! said Birbal, imitating the voice of his child.
Akbar asked his servants to milk the cow and give to Birbal.
The servants quickly milked the cow and offered the milk to Birbal. He sipped in a little and then gave the bowl to the emperor.
As Birbal put up the next demand that was put up by his child a few hours ago, the emperor was stunned and left the room.
What did Birbal say?

Different lights make me strange by changing me into different sizes. What am I?

Your last good ping-pong ball fell into a narrow metal pipe embedded one foot deep in concrete.
How can you get it out undamaged, if all the tools you have are your tennis paddle, shoe laces, and plastic water bottle, which does not fit into the pipe?