#
Q.177. Which one is a wrong statement ?

(1) The value of m for ${d}_{z}2$ is zero.

(2) Total orbital angular momentum of electron in 's' orbital is equal to zero.

(3) The electronic configuration of N atom is

(4) An orbital is designated by three quantum numbers while an electron in an atom is designated by four quantum numbers.

The incorrect statement is 3

Reason: Electronic configuration of nitrogen is incorrect as there are 3 electron in 2p orbital of nitrogen and two electron have same spin (clockwise) while other electron has anticlockwise spin.

Hund's rule of maximum multiplicity states that if two or more orbitals of same energy are available, electrons first fill the available orbitals singly and then proceeds to fill them in pairs and have same spin.

Hund’s rule states that electron pairing in p, d and f orbitals cannot occur until each orbital of a given subshell contains one electron each or is singly occupied. Hence it accounts for the maximum number of unpaired electron and thus maximum electron spin (electron spin is ½ for each single electron).

Now , calculation of spin for electron in 2p orbital = (+ ½) + (+ ½) -(+ ½)

Total spin = (+ ½)

If all the electron in 2p orbital have same spin then = (+ ½)+(+ ½)+(+ ½)

Total spin = (+ 3/2)

So third statement is incorrect.

**
**