Answer:
3.) Pumice
Explanation:
"Pumice is widely used as an abrasive in soaps and cleaners. It is considered one of the softest abrasives on earth."
Answer:

Explanation:
The diagonal of a square is x units.
Let the side of a square is s.
Using pythagoras,

The area of the square is,
A = s²
So,

So, the area of a square is
sq units.
This is an example of a closed system