What four weights can be used to balance from 1 to 30 pounds?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.

What can you see in the middle of March and April that you can never see in any other month?

Why do Chinese men eat more rice than Japanese men do ?

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.

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

On a certain day, John celebrated his birthday. Two days later, his older twin brother Jacob celebrated his birthday.

Is this even possible? How can it be?