The most non-metallic element among the given elements is

1.	Be	2.	B
3.	Mg	4.	Al

The group of metals having positive value of electron gain enthalpy is :-

The correctly matched option is:-

1. ${\mathrm{Fe}}^{+3}>{\mathrm{Fe}}^{+2}$ $>$ ${\mathrm{Fe}}^{+}$  : Order of atomic radius 

2. O > C > B > N   : Order of ionisation energy 

3. ${\mathrm{O}}^{-2}$ $<{\mathrm{O}}^{-}$ $<\mathrm{O}$ $<{\mathrm{O}}^{+}$ :  Increasing order of Z_eff

4. O < N < F < Ne  :  Order of electron affinity

Element of the third period that is expected to exhibit positive electron gain enthalpy is: 

The increasing order of non-metallic character of the elements N, P, O, and S is: 

1. P < S < N < O

2. O < S < N < P 

3. O < N < S < P 

4. N < S < O < P

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

A configuration with the lowest ionization enthalpy among the following is:
1. \(1 s^2 2 s^2 2 p^5\)$\mathrm{}$\(1 s^2 2 s^2 2 p^5\)
2. \(1 s^2 2 s^2 2 p^3\)
3. \(1 s^2 2 s^2 2 p^6 3 s^1\)
4. \(1 s^2 2 s^2 2 p^6\)

The correct order of the decreasing ionic radii among the following isoelectronic species is:

1. $C{a}^{2+}>K^{+}>S^{2-}>C{l}^{-}$

2. $C{l}^{-}>S^{2-}>C{a}^{2+}>K^{+}$

3. $S^{2-}>C{l}^{-}>K^{+}>C{a}^{2+}$

4. $K^{+}>C{a}^{2+}>C{l}^{-}>S^{2-}$

The correct order of ionic radii is:

1. $H^{-}>H^{+}>H$ $$
2. $N{a}^{+}>F^{-}>O^{2-}$
3. $F^{-}>O^{2-}>N{a}^{+}$
4. $N^{3-}>M{g}^{2+}>A{l}^{3+}$

Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^3$, the simplest formula for this compound is: 

1. ${\mathrm{Mg}}_2{\mathrm{X}}_3$

2. ${\mathrm{MgX}}_2$

3. ${\mathrm{Mg}}_2\mathrm{X}$

4. ${\mathrm{Mg}}_3{\mathrm{X}}_2$