The more of this there is, the less you see. What is it?

One day, John and his friends were playing around. Jacob hit something with a Pin and it popped. John's dad came into the room that very moment, but he wasn't mad. In fact, he was smiling. What did Jacob hit?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

What is the riddle which can be asked all day with a different correct answer each time.

Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?

What is more useful when it is broken?

Before Mount Everest was discovered, what was the highest mountain in the world?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?