What is the next number in this series?

4,12,84,3612....

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

Where do you go to learn how to make ice cream?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

By what process could you make a 'Tea-Table' into food?

What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?