What has no start, end, or centre?

Which of the eight images will fill the missing image in the puzzle below?

10+10 and 11+11 can give you the same answer.

Explain how?

What is the next number in this series?

4,12,84,3612....

You are on a Boat in the mid of a river. You have two cigarettes with you. One of these two you have to light, how will you light the cigarette?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

There is a bag which have 21 blue balls and 23 red balls. You also have 22 red balls outside the bag. Randomly remove two balls from the bag. * If they are of different colors, put the blue one back in the bag. * If they are the same colour, take them out and put a red ball back in the bag. Repeat this until only one ball remains in the bag. What is the color of the sole ball left in the bag ?

If,

Akriti = 631
Levis = 521
Sroti = 521
Aneel = 533
Then,
Sunil =?

Count the number of lines in the image below ?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?