Assertion (A) Atoms with completely filled and half-filled subshells are stable.
Reason (R ) Completely filled and half filled subshells have symmetrical distribution of electrons and have maximum exchange energy.
The correct answers is

Options

A. (A) and (R ) correct, (R ) is the correct explanation of (A)
B. (A) and (R ) are correct (R ) is not the correct explanation of (A)
C. (A) is correct but (R ) is not correct
D. (A) is not correct but (R ) is correct

Answer

a

Explanation

The extra stability of half-lined and fully filled electronic configuration can be explained in terms of symmetry and exchange energy. All the orbitals of the same subshell are either completely filled or half-filled have more symmetrical distribution of electrons consequently, their shielding of one another is relatively small and the electrons are more strongly attracted by the nucleus. This leads to more stability of the atom.