Question detail
Calculate the number of moles in 50 g of sodium chloride (NaCl).
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Mathematical requirements and assessment objectives
Question
- A. 0.43 mol
- B. 0.85 mol
- C. 1.07 mol
- D. 2.14 mol
Answer
0.43 mol
Explanation
The correct option is 0.43 mol. Use Moles From Mass: moles = mass / Mr. The worked result is 0.43 mol. 0.43 mol is the best answer because it directly supports the AQA A-Level Chemistry objective to rearrange equations and use algebra in physical chemistry. This reasoning is anchored to Mathematical requirements in Mathematical requirements and assessment objectives, and it separates algebra from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Rearranging Equations Mistake
Students often forget to isolate the variable correctly when rearranging equations, leading to incorrect results.
To fix this, always perform the same operation on both sides of the equation to maintain equality. For example, if you need to rearrange the equation for concentration (c = m/V) to find volume (V), you would multiply both sides by V and then divide by c: V = m/c. This ensures the variable is isolated correctly.
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