Question detail
An ion of element X has a mass number of 20 and contains 10 neutrons. Determine the number of protons and electrons in the ion if it has a charge of +1.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Atomic structure
Question
An ion of element X has a mass number of 20 and contains 10 neutrons. Determine the number of protons and electrons in the ion if it has a charge of +1.
Answer
The ion has 10 protons and 9 electrons. This answer is anchored to Mass number, isotopes and mass spectrometry.
Explanation
The ion has 10 protons and 9 electrons. is the best answer because it directly supports the AQA A-Level Chemistry objective to report isotope and mass-spectrometry calculations to an appropriate number of significant figures. This reasoning is anchored to Mass number, isotopes and mass spectrometry in Atomic structure, and it separates isotope 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
Significant Figures Mistake
Students often report the relative atomic mass of an isotope without considering significant figures, leading to inaccurate results.
To fix this, identify the number of significant figures required based on the data provided. For example, if the isotopic abundance data is given to three significant figures, ensure your final answer is also reported to three significant figures. Use the formula for relative atomic mass: relative atomic mass = (Σ(isotopic mass × abundance)) / Σ(abundance). Substitute the values, perform the calculation, and round the final answer appropriately.
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