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

Boron has lesser ionization enthalpy than Beryllium, because -

Among the following elements, the one that is not an actinoid is:

The order of screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on electrons in its outer shell is :

1. s > p > d > f

2. f > d > p > s

3. p < d < f < s

4. f > p > s > d

The first ionisation enthalpies of Na, Mg, Al, and Si are in the order of-

1. Na < Al < Mg < Si

2. Na > Mg > Al > Si

3. Na < Mg < Al < Si

4. Na > Mg > Al < Si

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

The correct order of size of the given species is: 

1.  I > I^- > I⁺

2.  I⁺ > I^- > I

3.  I > I⁺ > I^-

4.  I^- > I > I⁺

The outermost electronic configuration of the last element of the p-block in the 6th period is represented by:

1. $7{\mathrm{s}}^{2}7{\mathrm{p}}^6$

2. $5{\mathrm{f}}^{14}6{\mathrm{d}}^{10}7{\mathrm{s}}^{2}7{\mathrm{p}}^0$

3. $4{\mathrm{f}}^{14}5{\mathrm{d}}^{10}6{\mathrm{s}}^{2}6{\mathrm{p}}^6$

4. $4{\mathrm{f}}^{14}5{\mathrm{d}}^{10}6{\mathrm{s}}^{2}6{\mathrm{p}}^4$

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

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