Why 1729 is a magic number? Answer Logically.

It is always ahead of me yet I can never see it. What is it?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?

I’m tall when I’m young, and I’m short when I’m old. What am I?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

There are nine dots in the picture that has been attached with this question. Can you join all the dots by drawing four straight lines without picking up your pen?

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

If you read clockwise, you can form a word by inserting three missing letters in the picture given below. Can you do it?