Question detail

What is the mass number of an isotope?

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

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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
B. The total number of protons and electrons
C. The total number of neutrons only
D. The average mass of all isotopes

Answer

The correct option is The total number of protons and neutrons.

Explanation

The correct option is The total number of protons and neutrons. The total number of protons and neutrons is correct because it directly supports the approved learning objective to define isotopes as atoms of the same element with different numbers of neutrons. 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 9624e9d7 keeps this question distinct from adjacent atom, ion, isotope, group, period, and electronic-structure questions.

Common mistake

Misunderstanding Isotopes

Students often think isotopes are different elements rather than different forms of the same element.

Remember that isotopes are variations of the same element, distinguished only by their neutron count.

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