| A. | Unlike Ga that has a very high melting point, Cs has a very low melting point. |
| B. | On Pauling scale, the electronegativity values of N and Cl are not the same. |
| C. | \(Ar, K^+, Cl^-, Ca^{2+}\) and \(S^{2-}\) are all isoelectronic species. |
| D. | The correct order of the first ionization enthalpies of Na, Mg, Al, and Si is Si > Al > Mg > Na |
| E. | The atomic radius of Cs is greater than that of Li and Rb. |
| 1. | C and D only |
| 2. | A, C and E only |
| 3. | A, B and E only |
| 4. | C and E only |
| 1. | \(\mathrm{Na^+ , Cl^-, O^- , NO^+}\) | 2. | \(\mathrm{N_2O, N_2O_4 , NO^+, NO}\) |
| 3. | \(\mathrm{Na^+ , Mg^{2+} , O^- , F^-}\) | 4. | \(\mathrm{Ca^{2+} , Ar, K^+, Cl^-}\) |
| 1. | X is an alkali metal and Y is an alkaline earth metal. |
| 2. | X is an alkaline earth metal and Y is an alkali metal. |
| 3. | Both X and Y are alkali metals. |
| 4. | Both X and Y are alkaline earth metals. |