Which alphabet is a part of our body?

I am white when I am dirty, and black when I am clean. What am I?

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

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?

Living above a star, I do not burn
Eleven friends and they do not turn
I can just be visited in a sequence, not once or repeatedly
PQRS are my initials
Can you tell my name accurately?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

While preparing the table for dinner, wife came up with an idea to tease his mathematician husband. She asked her husband to pick nine toothpicks and make ten without breaking any toothpick.

The husband was also smart and did it within seconds. How ?

You walk into a room where there are three primates held in their respective cages:
1) A lion who is eating the flesh of a goat.
2) An orangutan who is playing with blocks.
3) A donkey who is sitting idle.

Who is the most intelligent primate in the room?