Can it be possible to build a house that has all its four walls facing towards the South?

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?

Dwayne Johnson was running away with the loot from a heist in his car along with Vin Diesel. One tire was punctured and he dropped down to replace it. While changing the wheel, he dropped the four nuts that were holding the wheel and they fell into a drain. Vin Diesel gave him an idea using which they were able to drive till the rendezvous point.

What was the idea ?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

I can be cracked, made, told, and played. What am I?

Move four matchsticks to the below square to form three squares?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.