Question

2(a) define the term isotope.

mark point 1: same element / same number of protons

Explanation:

Identify definition criteria

An isotope is defined by two key criteria:

1. Atoms of the same element containing the same number of protons.
2. Atoms containing a different number of neutrons (or having a different mass number).

Answer:

Atoms of the same element with the same number of protons but different numbers of neutrons.