Isotopes share atomic number but differ in mass number

Steps:

• Isotopes are variants of the same element with identical atomic numbers (protons) but different mass numbers (neutrons).
• For neutral atoms, electron number equals proton number, so isotopes have the same electrons.
• Evaluate choices: A matches electron equality; B contradicts same protons; C fits neutron difference; D contradicts neutron difference.
• Select A as it correctly describes neutral atoms.

Why A is correct:

• By definition, isotopes have the same atomic number, so neutral atoms have equal protons and thus equal electrons to maintain charge neutrality.

Why the others are wrong:

• B: Isotopes have the same number of protons in their nuclei.
• C: While true, the question asks for the correct statement among options, but A is the precise match for neutral atoms.
• D: Isotopes differ in neutron count, defining their distinction.

Final answer: A