What four weights can be used to balance from 1 to 30 pounds?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

Find three numbers such that When we multiply three numbers, we will get the prime numbers. The difference between the second and the first number is equal to the third and second.

Replace the question mark with the number below given a simple math problem.

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

A word I know has six letters it contains, remove one letter and 12 remain. What is it?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

There is so small cabin inside a deep forest.
All the forest burned out to worst possible but the inside of the cabin is still the same.
However all the person inside the cabin die.

How come ?

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?