The formation of oxide ion O2-(g), from 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 unfavourable even though O2- is isoelectronic with neon. It is due to the fact that:
1. | Oxygen is more electronegative |
2. | Addition of electron in oxygen results in a larger size of the ion |
3. | Electron repulsion outweighs the stability gained by achieving noble gas configuration |
4. | O- ion has comparatively smaller size than oxygen atom |
The outermost electronic configuration of the last element of the p-block in the 6th period is represented by:
1.
2.
3.
4.
The elements with atomic numbers 35, 53, and 85 are:
1. | Noble gases | 2. | Halogens |
3. | Heavy metals | 4. | Light metals |
Electronic configuration of four elements A, B, C and D are given below :
A.
B.
C.
D.
The correct order of increasing tendency to gain electron is :
1. | A < C < B < D | 2. | A < B < C < D |
3. | D < B < C < A | 4. | D < A < B < C |
Match the correct atomic radius with the corresponding element.
Element |
Atomic radius (pm) |
||
A. |
Be |
i. |
74 |
B. |
C |
ii. |
85 |
C. |
O |
iii. |
112 |
D. |
B |
iv. |
77 |
E. |
N |
v. |
66 |
Codes :
Options: | A | B | C | D | E |
1. | i | ii | iii | iv | v |
2. | iii | iv | v | ii | i |
3. | iv | ii | iii | i | v |
4. | v | ii | i | iii | iv |
Match the correct ionization enthalpies and electron gain enthalpies of the following elements.
Elements |
|
|
|
||
(i) |
Most reactive non-metal |
A. |
419 |
3051 |
-48 |
(ii) |
Most reactive metal |
B. |
1681 |
3374 |
-328 |
(iii) |
Least reactive element |
C. |
738 |
1451 |
-40 |
(iv) |
Metal forming binary halide |
D. |
2372 |
5251 |
+48 |
Codes
A | B | C | D | |
1. | ii | i | iv | iii |
2. | i | ii | iii | iv |
3. | i | iv | iii | ii |
4. | iv | i | iii | ii |
Electronic configuration of some elements is given in Column I and their electron gain enthalpies are given in Column II. Match the electronic configuration with electron gain enthalpy.
Column I (Electron configuration) |
Column II (Electron gain enthalpy/kJ mol–1) |
||
A. | 1. |
–53 |
|
B. | 2. |
–328 |
|
C. | 3. |
–141 |
|
D. | 4. |
+48 |
Codes:
Options: | A | B | C | D |
1. | 4 | 1 | 2 | 3 |
2. | 1 | 2 | 3 | 5 |
3. | 1 | 4 | 3 | 2 |
4. | 4 | 1 | 3 | 2 |
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. |
Given below are two statements:
Assertion (A): | Boron has a smaller first ionisation enthalpy than beryllium. |
Reason (R): | The penetration of 2s electron to the nucleus is more than the 2p electron hence 2p electron is more shielded by the inner core of electrons than the 2s electrons. |
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. |