I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

If an electric train is travelling south, then which way is the smoke going?

What has no start, end, or centre?

I know a nine-letter word having only one vowel.
Do you ?

A man had five children. He had $100 with him to give to his children. He decided to start with the youngest child and then give $2 more than each younger child to his next elder child.

For example, if he gives $x to the youngest child, he will give $(x+2) to the next one, $[(x+2) + 2] to the next one and so on.

Can you find out how much did the youngest one receive?

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

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.

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Paul's height is six feet, he's an assistant at a butcher's shop and wears size 9 shoes. What does he weigh?