What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

There is a place where if I stand up straight, I will still be considered sideways.

I have no life, but I can die. What am I?

There was a strange boy who was born before his father. How can this be possible?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

During an experiment, a guy throws a bouncy ball from a 100 feet tall building. The ball has a specific characteristic. Every time it hits the ground, it bounces up halfway.

How many bounces do you think the ball will make before it comes to a stop ?

There is a square piece of paper with a hole that is denoted by the circle on the top right side in the given picture. You have to cut the paper in a manner that it forms two and only two separate pieces of paper and then rearrange the pieces in a manner that the holes come in the centre of the paper.

Christina is practising her dance steps along with her friends. In a particular sequence, all of them form a row. At that point, Niharika is standing in the 4th position from either end of the row.
Can you find out how many girls are practising together?