I have an eye but still cannot see.

Who am I?

Whats the next number in the below number sequence pattern.

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

You walk into a creepy house by yourself. There is no electricity, plumbing, or ventilation. Inside you notice 3 doors with numbers on them. Once you open the doors you will die a particular way. Door No.1 You’ll be eaten by a lion who is hungry. Door No.2 You’ll be stabbed to death. Door No.3 There is an electric chair waiting for you. Which door do you pick?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

The husband and wife were jogging in the morning. To match every two steps of the husband, the wife required three steps. If Both of them start with the here right foot. After how many steps do their left foot be together?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

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

The centre of the third figure is empty. What digit should fit inside?