what are four examples of solution for which the concentration must be known?

6 answers

I don't understand the question. I made an error in the last post; I'll tell you here instead of there. In the ratio 10.0/20.0 = 0.500, you are allowed three places and not two as I wrote. If you can explain this another way perhaps I can help.
The exact question is like this.describe four examples of solutions for which the concentration must be known and exact. (E.g drinking water)
I suppose you can use drinking water as one. Another might be drugs (medicines). I think food products, too, although the EXACT value may be rounded on the package label. See if you can think of a fourth.
The question says SOLUTIONS?
Some medicines are liquids. Some food is liquid (milk etc,)
Ok but I can't use water cause its already in question I need some other.