Answer:
For question 4.1, the proton numbers of the neutral X, Y, and Z are the same, since the number of protons is determined by the atomic number, which remains unchanged regardless of the ion's charge. So, if X has an atomic number of 3, Y and Z also have an atomic number of 3.
For question 4.2, the atomic number of S is 16, since S-2 and Ca+2 have the same number of electrons and the atomic number of Ca is 20. Since the atomic number is equal to the number of protons, then S must have 16 protons.
For question 4.3, Y must have 11 protons. Since X has an atomic number of 14, then it has 14 protons, and since X3- and Y2+ have the same number of electrons, then Y must have 11 protons in order to balance out the charges.
For question 4.4, X must have 15 protons. Since P5+ and X-1 have the same number of electrons, then X must have 15 protons in order to balance out the charges, and since the atomic number is equal to the number of protons, then X must have an atomic number of 15.
For question 4.5, X must have 18 protons. Since X3- and Y2+ have the same number of electrons, and the sum of electrons is 36, then X must have 18 protons in order to balance out the charges, and since the atomic number is equal to the number of protons, then X must have an atomic number of 18.