Consider the following ionization enthalpies of two elements ‘A’ and ‘B’. Which of the following statements is correct ?

Question

Consider the following ionization enthalpies of two elements ‘A’ and ‘B’.

Element	Ionization	enthalpy	(kJ/mol)
	1st	2nd	3rd
A	899	1757	14847
B	737	1450	7731

Which of the following statements is correct ?

(a) Both ‘A’ and ‘B’ belong to group–1 where ‘B’ comes below ‘A’.

(b) Both ‘A’ and ‘B’ belong to group–1 where ‘A’ comes below ‘B’.

(c) Both ‘A’ and ‘B’ belong to group–2 where ‘B’ comes below ‘A’.

(d) Both ‘A’ and ‘B’ belong to group–2 where ‘A’ comes below ‘B’.

Answer 1

Correct option: (c) Both ‘A’ and ‘B’ belong to group–2 where ‘B’ comes below ‘A’.

Explanation:

Generally, the ionization enthalpies or energy increases from left to right in a period and decreases from top to bottom in a group. Several factor such as atomic radius, nuclear charge, shielding effect are responsible for change of ionization enthalpies.

Here, Ist ionization enthalpy of A and B is greater than group I (Li 520 kJmol–1 to Cs374 kJmol^–1), which means element A and B belong to group –2 and all three given ionization enthalpy values are less for element B means B will come below A.