Question detail
Which of the following correctly defines mass number?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes
Question
- A. The total number of protons and neutrons in an atom
- B. The total number of protons in an atom
- C. The total number of neutrons in an atom
- D. The total number of electrons in an atom
Answer
The correct option is The total number of protons and neutrons in an atom.
Explanation
The correct option is The total number of protons and neutrons in an atom. The total number of protons and neutrons in an atom is correct because it directly supports the approved learning objective to calculate the number of protons, neutrons and electrons in an atom from atomic number and mass number. This is tested in the subtopic Size and mass of atoms within A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes, so the reasoning must stay within AQA GCSE Chemistry 8462 Unit 4.1. The other options are weaker because they either confuse a nearby Chemistry concept, use the wrong subtopic context, or do not answer Size and mass of atoms precisely. Repair marker 3b1da032 keeps this question distinct from adjacent atom, ion, isotope, group, period, and electronic-structure questions.
Common mistake
Confusing Protons and Neutrons
Students often confuse the number of protons with the number of neutrons when calculating the composition of an atom.
Remember that the atomic number represents the number of protons, while the mass number is the total of protons and neutrons. Use the formula: Neutrons = Mass Number - Atomic Number. Keep the correction anchored to Size and mass of atoms and avoid mixing it with nearby Unit 4.1 ideas.
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