Question detail

How do isotopes of the same element differ?

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

Atoms and isotopes

Question

A. By their number of protons
B. By their number of neutrons
C. By their number of electrons
D. By their chemical reactivity

Answer

The correct answer is B: By their number of neutrons.

Explanation

The correct answer is B: By their number of neutrons. This supports the learning objective "Define isotopes as atoms of the same element with different numbers of neutrons." in Mass number, atomic number and isotopes because it uses the correct atomic and nuclear radiation relationship for Atoms and isotopes. The other options are less suitable because they do not match the required Mass number, atomic number and isotopes idea: By their number of protons; By their number of electrons; By their chemical reactivity.

Common mistake

Misidentifying Isotopes

Students often think that isotopes differ in the number of protons rather than neutrons, so they describe isotopes as having different atomic numbers.

Remind that isotopes are atoms of the same element (same atomic number) that have different numbers of neutrons, giving them different mass numbers.

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