Can you find a number that lies one third of the distance between 1/3 and 2/3?

Find the missing number in the sequence below:

If you say my name, I will no longer exist. What am I?

What came first, the chicken or the egg?

Can you find a five letter word that is left with only two letters if one is removed?

With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?

What is full of holes but still holds water?

It belongs to you, but other people use it more than you do. What is it?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?

You are playing a game with your friend Jack. There are digits from 1 to 9. You both will take turn erasing one digit and adding it to your score. The first one to score 15 points will win the game.

Would you want to play first or second?

PS: The sum should be exactly 15.