Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

This is a picture puzzle. You have to guess the name of the movie that can be related to the picture.

A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

Here is what you have to do. You have to throw a ball as hard as you can but it must return back to you even if it does not bounce at anything. Also, you have nothing attached to the ball. There is no one on the other end to catch that ball and throw it back at you.

How will you do it?

You can hear me, but you can't touch or see me.

What am I?

I shave every day, but my beard stays the same. What am I?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?