Subatomic particles in the S²⁻ ion from sulfur-34 isotope

Steps:

• Sulfur's atomic number is 16, so S²⁻ has 16 protons.
• The -2 charge means the ion has gained 2 electrons, for a total of 18 electrons.
• The mass number for this sulfur isotope is 34, so neutrons = mass number - protons = 34 - 16 = 18.
• Thus, S²⁻ has 16 protons, 18 neutrons, and 18 electrons.

Why B is correct:

• It matches the proton count from atomic number 16, electron count for the -2 ion charge (protons + 2), and neutron count for mass number 34 (34 - 16).

Why the others are wrong:

• A: 16 electrons indicate a neutral atom, not the anion.
• C: 16 neutrons fit mass 32 isotope, not 34.
• D: 20 protons correspond to calcium, not sulfur.

Final answer: B