Answer: Option (A) is the correct answer.
Explanation:
When an atom gains an electron, it attains a negative charge and the number of electrons in that atom increases. Whereas if an atom looses an electron, it attains a positive charge and the number of electrons in that atom decreases.
Atomic number of chlorine is 17 that is there are 17 electrons in a neutral Cl atom. Therefore, in a \(Cl^{-}\) ion there are 17 + 1 = 18 electrons.
Atomic number of sulfur atom is 16 that is there are 16 electrons in one neutral S atom. Therefore, in a \(S^{2-}\) ion there are 16 + 2 = 18 electrons.
Atomic number of bromine is 35 that is there are 35 electrons in a neutral Br atom. Therefore, in a \(Br^{-}\) ion there are 35 + 1 = 36 electrons.
Atomic number of magnesium is 12 that is there are 12 electrons in a neutral Mg atom. Therefore, in a \(Mg^{2+}\) ion there are 12 - 2 = 10 electrons.
Atomic number of sodium is 11 that is there are 11 electrons in a neutral Na atom. Therefore, in a \(Na^{+}\) ion there are 11 - 1 = 10 electrons.
Thus, we can conclude that \(Cl^{-}\) and \(S^{2-}\) ions contain same total number of electrons.