| 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. | Li < B < Be < C < N | 2. | Li < Be < C < B < N |
| 3. | Li < Be < N < B < C | 4. | Li < Be < B < C < N |
| 1. | The oxidation state and coordination number (or covalency) of \(\mathrm{Al}\) in\( \left[\mathrm{AlCl}\left(\mathrm{{H}_2 {O}}\right)_5\right]^{2+} \) are +3 and 6, respectively. |
| 2. | \(\mathrm{Na}_2 \mathrm{O}\) is a basic oxide and \(\mathrm{Cl}_2 \mathrm{O}_7\) is an acidic oxide |
| 3. | The following four species are called isoelectronic species: \( \mathrm{O}^{2-}, \mathrm{F}^{-}, \mathrm{Na}^{+} \mathrm{and}~ \mathrm{Mg}^{2+}\) |
| 4. | Among the four species \(\mathrm{Mg}, \mathrm{Al}, \mathrm{Mg}^{2+}\) and \(\mathrm{A l^{3+},}\) the smallest one is \(\mathrm{Al}.\) |
| 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. |
| 1. | C < N < F < O | 2. | C < N < O < F |
| 3. | C < O < N < F | 4. | C < F < N < O |
For the second-period elements, the correct increasing order of first ionisation enthalpy is:
| 1. | Li < Be < B < C < O < N < F < Ne |
| 2. | Li < Be < B < C < N < O < F < Ne |
| 3. | Li < B < Be < C < O < N < F < Ne |
| 4. | Li < B < Be < C < N < O < F < Ne |