Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

Who has married many women but was never married?

In which direction should the missing arrow point?

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.

I am sure no one can have two things for dinner. what are they?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

All Marigolds are flowers.
Few Flowers are used to make colors.
Therefore, some Marigold are used to make colors.

True Or False?

Can you find the key in the picture below?

What does this rebus riddle mean?