Question

Which statements describe isotopes? Check all that apply.

Isotopes of the same element have the same number of protons.
Isotopes of the same element have the same number of neutrons.
All isotopes are unstable.
Some isotopes are unstable.
Isotopes are identified by their mass number.
Isotopes are identified by their atomic number.

Answer 1

Correct:
- Isotopes of the same element have the same number of protons. (True — same atomic number.)
- Some isotopes are unstable. (True — some are radioactive, others are stable.)
- Isotopes are identified by their mass number. (True — e.g., C-12, C-14; the mass number A distinguishes isotopes.)

Incorrect:
- Isotopes of the same element have the same number of neutrons. (False — they differ in neutron count.)
- Isotopes are identified by their atomic number. (False — the atomic number is the same for all isotopes of an element and identifies the element, not the specific isotope.)