Why do people go to bed?

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?

I start and end with 500 and carry a 5 in my heart. But I require the first letter and the first number to be complete. I am the name of a King.

Who am I ?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

The cream is heavier than Milk. True or False?

Count the number of balls in picture below:

Assume the given figure to be a delicious doughnut. Yes, now you can concentrate more on the puzzle. So you have this delicious doughnut in your refrigerator when your friends come knocking at the door. There are eight of them. Now you have to make three cuts in this doughnut so that each one of you nine people can enjoy a piece of it. Neither you nor your friends would mind the size of their piece as long as they are getting it. How will you do it?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

There are four people in a house. A fireman, an athlete, an old woman, and a drunk guy. The house catches fire and before the fact is known, it is too late. All they know is that the entire house is in flames and it will collapse exactly after twelve minutes. Now they can move out of the house but for that, they will have to pass the hallway which is entirely blazing with flames. Thus to move, one must carry a fire extinguisher to keep the flames away. Seeking the burnt wooden floor, only two people can run through that hallway at one time. But for others to go, one must return back with the fire extinguisher. The fireman is trained for such tasks and can run through the hallway in a minute. The athlete can make it in a couple of minutes. The old woman can run slowly and will cover the hallway in four minutes. The drunk guy will take five minutes to run through it. If all of them can make it through the hallway in twelve minutes, all of them will be saved. When two move together, they will run at the speed of the slower ones.

How will all four of them manage to run to safety?