The illustration is clear / unambiguous in representing complete ionisation and thus a strong acid in the solvent.
If the solvent is water, using H
+ rather than H
3O
+ is unfortunate in that it suggests an Arrhenius theory perspective / model (where strength was not described) rather that a LB model. The model could be a strong acid in a solvent where ionisation occurs but the proton (H
+ ion) produced does not interact with the solvent... though I struggle to imagine what that solvent might be.
The interpretation of this diagram as representing a concentrated or dilute solution is much more subjective. There are only two cations and anions, which might suggest a low concentration, though their scale does appear to occupy much of the volume / box. Attempting to interpret a scale requires assumptions that are difficult to justify as the H
+ and A
- ions are the same size, and there is no anion, not even the hydride anion H
-, that has a size that is near identical to a single proton. A second diagram of comparable size could illustrate a second solution where relative concentrations could be compared, but attributing and absolute concentration descriptor here is unlikely to be objectively reasonable in this sort of example, in my opinion.
I do agree with
@wizzkids that questions with issues that more able students will notice and then attempt to address are poor assessment items and unfair. I recall a questions in the past where a mixture of five substances was dissolved, solids S
1, S
2, and S
3, and liquids L
1 and L
2. The liquids were immiscible. S
1 was soluble in L
1 but not in L
2. S
2 was soluble in L
2 but not in L
1. S
3 was not soluble in L
1 nor in L
2. A method for separating the mixture into its components was sought.
The intended answer was to filter to collect S
3, then separate the immiscible layers of L
1 and L
2 using a separating funnel, then evaporate each solvent in a distillation apparatus to recover S
1 and S
2 as solids while recondensing the pure liquids L
1 and L
2.
However, some more capable students recognised that this method assumed that there was enough of the L
1 so that all of the S
1 was dissolved in that layer, and similarly for S
2 and L
2. If this were not the case, then the filtration step would yield a mixture that could contain S
1, S
2, and S
3. Now, further liquids L
1 and / or L
2 could be added to the solid mix, but what if extra liquid was not supplied and this needed to be recycled after it was purified as above?
The answers became increasingly complicated, robbing more able students of valuable time, all arising because the question did not give any guidance on the quantities present. Students who didn't notice / care about this omission were then advantaged over those who did realise that quantities mattered. The mistake by the examiner left a question that appeared to have a trick that disadvantaging those who noticed it and inferred that the examiner intended for quantities to be considered.
It was a five mark, outline a method type question, so the intended answer did appear to involve too little for the marks, which added to the confusion on interpretation.
In short, wizzkids is right that bad question writing can disadvantage the more able students who recognise ambiguities and flaws.
