Question

in which of the following sets are the charges given correctly for all the ions?
○ rb-, ba2-, p3+
○ k+, sr2+, o2-
○ n-, o2-, f3-
○ na+, mg+, al+

Explanation:

• For \(Rb\) (rubidium, group 1), the common ion is \(Rb^{+}\) (loses 1 electron), \(Ba\) (barium, group 2) forms \(Ba^{2 +}\) (loses 2 electrons), and \(P\) (phosphorus, group 15) forms \(P^{3 -}\) (gains 3 electrons). So \(Rb^{-},Ba^{2 -},P^{3+}\) is incorrect.
• \(K\) (potassium, group 1) forms \(K^{+}\) (loses 1 electron), \(Sr\) (strontium, group 2) forms \(Sr^{2+}\) (loses 2 electrons), \(O\) (oxygen, group 16) forms \(O^{2 -}\) (gains 2 electrons). This set has correct ion - charges.
• \(N\) (nitrogen, group 15) forms \(N^{3 -}\) (gains 3 electrons), \(F\) (fluorine, group 17) forms \(F^{-}\) (gains 1 electron). So \(N^{-},O^{2 -},F^{3 -}\) is incorrect.
• \(Mg\) (magnesium, group 2) forms \(Mg^{2+}\) (loses 2 electrons), \(Al\) (aluminium, group 13) forms \(Al^{3+}\) (loses 3 electrons). So \(Na^{+},Mg^{+},Al^{+}\) is incorrect.

Answer:

\(K^{+},Sr^{2 +},O^{2 -}\)