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

What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

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

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

It is a nine-letter word.
The exact opposite of the phrase "friendly and outgoing"
It contains the word "over".
It starts will a vowel.

What is it?