Elements	$∆H_1$	$∆H_2$	${∆}_{eg}H$
I	520	7300	-60
II	419	3051	-48
III	1681	3374	-328
IV	1008	1846	-295
V	2372	5251	+48
VI	738	1451	-40

The least reactive element based on the above data is:

1. III
2. IV
3. II
4. V

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

Which of the following correctly represents the order of electron gain enthalpy
(energy released on gaining an electron) among halogens?

In the modern periodic table, the period number directly signifies which of the following characteristics for the elements belonging to that period?

The elements in which electrons are progressively filled in 4f-orbitals are called:

The correct order of size of the given species is: 

Which of the following represents the valence shell electronic configuration of the last element of p-block, located in the 6th period?

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