I believe the answer would be C, unbalanced.
Since the forces are in opposite directions, and aren't the same size, the answer would be unbalanced.
So what am I suppose to answer here?
Answer: dilute
Explanation:
A concentrated solution which is used to prepare solutions of lower concentrations by diluting it with addition of water.
A dilute solution is one which contains lower concentration.
Using Molarity equation:
=concentration of stock solution = 0.150 mol/L
= volume of stock solution = 10.0 ml
= concentration of dilute solution = ?
= volume of dilute solution = (10.0+90.0) ml = 100.0 ml


As the concentration is less than the original concentration, the solution is termed as dilute.
H₂S
<h3>Further explanation</h3>
Given
ΔH fusion and ΔH vaporization of different substances
Required
The substance absorbs 58.16 kJ of energy when 3.11 mol vaporizes
Solution
We can use the formula :

Q=heat/energy absorbed
n = moles
The heat absorbed : 58.16 kJ
moles = 3.11
so ΔH vaporization :

The correct substance which has ΔH vaporization = 18.7 kj / mol is H₂S
(H₂S from the data above has ΔH fusion = 2.37 kj / mol and ΔH vaporization = 18.7 kj / mol)