There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

What does this rebus mean?

O
N
C
E
TIME

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

When is the top of a mountain similar to a savings account?

A Child was born in Lahore, Pakistan. Still, the child is not a Pakistani citizen. why?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?