Question

The set representing the correct order of first ionisation potential is

(A) K > Na > Li
(B) Be > Mg > Ca
(C) B > C > N
(D) Ge < Si > C​

Answer 1

Explanation:

answer-B

Down the group the effective nuclear charge remains almost constant. But down the group with increasing atomic number the number of atomic orbits increases and thereby atomic size increases. As a result, the distance of valence shell electron from nucleus increases and attraction between them decreases and therefore ionization energy decreases.

The correct order will be

A. Li > Na > K

B. Be > Mg > Ca

C. N > C > B