Two Guards And Two Doors
Riddle: There are two guards and two doors, one door is the door that has an exit, the other is a trap and you will be trapped there forever. One guard is a liar and lies all the time, the other is honest and is always truthful, they look identical so there is no way to tell the difference between the liar and truthful guard. You have one question to ask them so you can guarantee which door is the exit. What is the question?
Answer: The answer is: "You ask what your "brother" or what the other guard would say the door is." the liar would lie and point to the wrong door, and the trustworthy one would tell the truth of what the liar would say and point at the wrong door. So you would go towards the opposite door, towards the exit.
Source: https://www.riddles.com/9522
