Question

Pick the correct order of ionization potential values of elements.

(a) C < O < N < F < Ne

(b) He > Ne > Ar > Kr > Xe

(c) Li > Na > K > Rb > Cs

(d) Be < Mg < Ca < Sr < Ba

(e) Na > Mg > Al > Si > P

• A. a, c and e
• B. b, c and d
• C. a, b and c
• D. b, d and c

Answer 1

Answer: (C)

a, b and c

Ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms. Atoms are more stable when they have full valence shells.

a) The IP increases towards the right side along a period. But elements of group 15 have higher IP than group 16 as they have half-filled orbitals. Thus correct order is C < O < N < F < Ne.

b) Noble Gases have a very stable electron configuration, therefore, they have the highest amount of ionization energy within their periods. It decreases down a family because electrons farther from the nucleus are easier to remove.

Ionization Energy levels of Noble Gases group in Descending Order :: He > Ne > Ar > Kr > Xe > Rn

c) As we move from top to bottom in a group the ionization energy will be decreased because the atomic radius will be increased so the removal of electron will be easy.

Li, Na, K, Rb, Cs are IA group elements from Li to Cs the ionization energy

will be decreased. So, the correct order of ionization energy is Cs < Rb < K < Na < Li

d) and e) are wrong.

Hence, a, b and c are correct.

Therefore, option C is correct.