<span>The student is incorrect because helium has 2 valence electrons and it's in group 18 because the first energy level is full. Although helium is placed in Group 18 which generally has 8 valence electrons, it does not have 8 valence electrons as the student suggested. It was grouped together with the noble gases because it exhibits similar properties with them. </span>
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.
Answer:
it increases and is perpendicular to the motion of the wave.
The answer is H20 thank me later

The explanation is shown in the image attached with