Adding solvent or removing solute from a solution is called diluting. And a solution is said to be concentrated if it has more solute. The opposite of diluting is called concentrating. The measure of the amount of solute in a solution is expressed in concentration.
The states of matter is solid,liquid and gas & you go from there.
I don’t know if this would help but my cousin said this: Molecular weight of chlorine = 71, so 7.1/71 = 0.1 mol of Cl2
