a. Determine the number of protons, neutrons, and electrons in a neutral iodine-127 atom.
b. The ion S^2– has _____ protons and _____ electrons.
c. What isotope has 17 protons and 18 neutrons? Write the element's name followed by a hyphen and the mass number (e.g. carbon–13).
d. Identify the element represented in the following expression: ⁷⁵₃₃X? Write the element's chemical symbol.