I have branches, but no fruit, trunk or leaves. What am I?

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?

What part of Turkey has the most feathers?

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?

What is black when you buy it, red when you use it, and gray when you throw it away?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

There are four 3-link chains. All you have to do is join them into a big 12-link chain. For joining two closed links, one of the links must be cut and placed onto the other link for closing.

How many minimum links will you have to cut to make the big chain?

Riddle me this, Riddle me that,
What am I? I am made of wood, but you can't see me down?