Pretty sure it’s a chemical change.
Preparing 15 mg/gl working standard solution from a 20 mg/dl stock solution will require the application of the dilution principle.
Recalling the principle:
initial volume x initial molarity = final volume x final molarity
Since we were not given any volume to work with, we can as well just take an arbitrary volume to be prepared. Let's assume that the stock solution is 10 mL and we want to prepare 15 mg/gl from it:
Applying the dilution principle:
10 x 20 = final volume x 15
final volume = 200/15
= 13.33 mL
This means that in order to prepare 13.33 mL, 15 mg/l working standard solution from 10 ml, 20 mg/dl stock solution, 3.33 mL of the diluent must be added to the stock solution.
More on dilution principle can be found here: brainly.com/question/11493179
I heard that most of the time water found in watersheds aren’t usually clean nor safe for drinking, but i know that there are very few that are somewhat safe for drinking. It’s just not usually common to find clean and healthy watersheds though.
Answer:
2 atoms of H in the products side
Explanation:
3NO₂ + H₂O → NO + 2HNO₃
In product side: 3 N (1 from NO and 6 from nitric acid), 7 O (6 from nitric acid + 1 from NO), 2 H
In reactant side: 3 N, 7 O (6 from the dioxide + 1 from water) and 2 H
