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

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

which number am I?

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?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?

What is harder to catch the faster you run?

Why are all black people so quick ?

John is 45 years older than his son Jacob. If you find similarities between their ages, both of their ages contain prime numbers as the digits. Also, John's age is the reverse of Jacob's age.

Can you find their ages?

Can you guess the name of the month by looking the below rebus ?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Here is what you have to do. You have to throw a ball as hard as you can but it must return back to you even if it does not bounce at anything. Also, you have nothing attached to the ball. There is no one on the other end to catch that ball and throw it back at you.

How will you do it?