There was an aeroplane crash, every single person died, but two people survived. How is this possible?

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

What jumps when it walks and sits when it stands?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

In a supermarket, there is an intelligent glass pane before a refrigerating unit. This glass pane allows cherries and apples through it but does not allow grapes and Orange to pass through it.

Can you identify the rule that the glass pane is following?

Why do you find that most of the buildings are deprived of the 13th floor?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.