The first step in the scientific methods is ask a question
The green and black symbols refer to atoms, that make up the molecule of water, more specifically you can say that the 2 Hydrogen atoms are the black ones found outside, while the central atom, that is also green would be oxygen.
Answer: Concentration of the chemist's sodium chloride solution is 34.4 mol/L.
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

where,
n= moles of solute
= volume of solution in ml
Given : moles of
= 6.89
volume of solution = 200 ml
Putting in the values we get:

Thus the concentration of the chemist's sodium chloride solution is 34.4 mol/L.
Valence électrons = are electrons in the outermost shell that is responsible for the chemical reactions of the atoms