Among halogens, the correct order of amount of energy released in electron gain (electron gain enthalpy) is-

The formation of oxide ion O^2-(g), from oxygen atom, requires first an exothermic and then an endothermic step as shown below

$\mathrm{O}\left(\mathrm{g}\right)+{\mathrm{e}}^{-}\to {\mathrm{O}}^{-}\left(\mathrm{g}\right); ∆{\mathrm{H}}^{⊝}=-141 \mathrm{kJ} {\mathrm{mol}}^{-1}$
${\mathrm{O}}^{-}\left(\mathrm{g}\right)+{\mathrm{e}}^{-}\to {\mathrm{O}}^2\left(\mathrm{g}\right); ∆{\mathrm{H}}^{⊝}=+780 \mathrm{kJ} {\mathrm{mol}}^{-1}$

Thus, the process of formation of O^2- in the gas phase is unfavourable even though O^2- is isoelectronic with neon. It is due to the fact that

Electronic configuration of four elements A, B, C and D are given below : 

A. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^6$

B. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^4$

C. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$

D. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^5$

The correct order of increasing tendency to gain electron is : 

Match the correct ionization enthalpies and electron gain enthalpies of the following elements.

Codes

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.

Codes

Given below are two statements: 

Given below are two statements: 

An element(s) that gain one electron more readily in comparison to other elements of their group is/are-

(a) S_(g)

(b) Na_(g)

(c) O_(g)

(d) Cl_(g)

Choose the correct option

1. (a), (d)

2. (b), (c)

3. (c), (d)

4. (b), (d)

Correct statement(s) among the following are-

Choose the correct option

1. (a), (c), (d)

2. (a), (b), (c)

3. (a), (c),

4. (a), (d)