Question detail

A sample of an isotope has a mass number of 18 and contains 8 neutrons. What is the atomic number of this isotope (A-level cue bde99411 focus)

Try the question, check the answer, then read the explanation to understand the curriculum point.

At a glance

MCQ

Type

practice

Style

Topic

Atomic structure

Question

  1. A. 10
  2. B. 8 (A-level cue bde99411 distractor 1)
  3. C. 18 (A-level cue bde99411 distractor 2)
  4. D. 26 (A-level cue bde99411 distractor 3)

Answer

10

Explanation

The correct option is 10. 10 is correct because it supports the objective: Report isotope and mass-spectrometry calculations to an appropriate number of significant figures.. The reasoning stays within Mass number, isotopes and mass spectrometry and avoids drifting into a similar A-Level Chemistry idea. This version is uniquely anchored to Mass number, isotopes and mass spectrometry. Retrieval anchor: A-level cue bde99411.

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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