- 1(current)
Q. No.Given below are two statements:
| Assertion (A): | Generally, ionisation enthalpy increases from left to right in a period. |
| Reason (R): | When successive electrons are added to the orbitals in the same principal quantum level, the shielding effect of inner core of electrons does not increase very much to compensate for the increased attraction of the electron to the nucleus. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
Subtopic: Ionization Energy (IE) | Electron Affinity (EA) |
76%
Level 2: 60%+
Hints
The formation of the oxide ion, O²⁻(g), from an oxygen atom occurs in two successive steps:
O(g) + e⁻ → O⁻(g) ΔH = −141 kJ mol⁻¹
O⁻(g) + e⁻ → O²⁻(g) ΔH = +780 kJ mol⁻¹
Although O²⁻ is isoelectronic with neon, its formation in the gaseous state is energetically unfavourable. What is the main reason for this?
| 1. | Electron repulsion outweighs the stability gained by achieving a 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. |
Subtopic: Electron Affinity (EA) |
76%
Level 2: 60%+
NEET - 2015
Hints
Links
Column I lists the electronic configurations of certain elements, while Column II provides their electron gain enthalpy values. Match each electronic configuration with the appropriate electron gain enthalpy:
| Column-I (Electron configuration) |
Column-II (Electron gain enthalpy/ kJ mol¯1) |
||
| A. | \(1 s^2 2 s^2 2 p^6\) | (i) | \(-53\) |
| B. | \(1 s^2 2 s^2 2 p^6 3 s^1\) | (ii) | \(-328\) |
| C. | \(1 s^2 2 s^2 2 p^5 \) | (iii) | \(-141\) |
| D. | \( 1 s^2 2 s^2 2 p^4 \) | (iv) | \(+48\) |
| Options: | A | B | C | D |
| 1. | (iv) | (i) | (ii) | (iii) |
| 2. | (i) | (ii) | (iii) | (iv) |
| 3. | (i) | (iv) | (iii) | (ii) |
| 4. | (iv) | (i) | (iii) | (ii) |
Subtopic: Electron Affinity (EA) |
74%
Level 2: 60%+
Hints
What is the correct order of electron gain enthalpy from least negative to most negative for the elements C, Ca, Al, F, and O?
1. Al < Ca < O < C < F
2. Al < O < C < Ca < F
3. C < F < O < Al < Ca
4. Ca < Al < C < O < F
1. Al < Ca < O < C < F
2. Al < O < C < Ca < F
3. C < F < O < Al < Ca
4. Ca < Al < C < O < F
Subtopic: Electron Affinity (EA) |
82%
Level 1: 80%+
NEET - 2013
Hints
- 1(current)
Q. No.
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