Complete the table series riddle by finding the number that can replace "??".

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

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

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Can you name some countries which do not have the alphabet 'A' in them?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

Vin Diesel is pulling a theft and has planned to run away with all the cash kept in the safe. But the only way to open the safe is the 13 character password. He has a set of five clues given to him by a trustworthy source.

Exactly two of the below statements are false.
The password is contained within this sentence.
The password is not in this hint.
The password is within only one of these statements.
At least one of the above statements is a lie.

Why do we preferably have round manhole covers and not square ones?