What's the only room from which no one can enter or leave

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

what's the probability of getting a king or a queen from a pack of 52 cards?

Can you move 2 matchsticks to form four equal sized squares.

In the image given, you can find several triangles. Can you count them all?

A dead body is found outside a multi-story multinational company. The case is reported and a homicide detective is called on the crime scene.

He looks at the body and then towards the building. From the position of the body, it is evident that the victim committed suicide. He goes to the first floor of the building and then walks in the direction of the dead body, opens the window and toss a coin in the air.

He goes to second floor and again repeats the process. He keeps doing this till he is done on all the floors. Then he returns back to the floor and tells his team that it is a murder.

How in heaven did he deduce that?

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

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

The picture shows the dice results in each couple of throws. If they are actually following a pattern, can you find out the missing one?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?