The formation of the oxide ion O2- (g), from the oxygen atom requires first an exothermic and then an endothermic step as shown below,
Thus, the process of formation of O2- in the gas phase is unfavorable even though O2- is isoelectronic with neon. It is due to the fact that:
1. | Electron repulsion outweighs the stability gained by achieving noble gas configuration. |
2. | O- ion has a comparatively smaller size than the oxygen atom. |
3. | Oxygen is more electronegative. |
4. | Addition of electrons in oxygen results in a large size of the ion. |
The value of electron gain enthalpy of Na+ if IE1 of Na = 5.1 eV ,is
1. + 10.2 eV
2. –5.1 eV
3. –10.2 eV
4. + 2.55 eV
The correct order of increasing electron affinity for the elements, O, S, F and Cl is:
1. | Cl < F < O < S | 2. | O < S < F < Cl |
3. | F < S < O < Cl | 4. | S < O < Cl < F |
Which one of the following arrangements does not give the correct picture of the trends indicated against it?
1. F2> Cl2> Br2> I2 : Oxidising power
2. F<Cl>Br>I : Electron gain enthalpy
3. F2> Cl2> Br2> I2 : Bond dissociation energy
4. F> Cl > Br > I : Electronegativity