What's the only room from which no one can enter or leave

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

What number divided by 4 is the same as that number minus 4?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

I am lying and I always lie. Tell me whether I am lying or telling the truth.

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

What has a bottom at the top?

Find the missing number in the image below.

John Went to the nearby store in a Mall to buy something for her home. Below is the conversation between the two:

John: How much for the one?
Shopkeeper: It is $2
John: How much for the Eleven?
Shopkeeper: It is $4
John: How much for the Hundred?
Shopkeeper: It is $6.

What is John buying?

In a stable, there are men and horses. In all, there are 22 heads and 72 feet. How many men and how many horses are in the stable