Test: Quantum Numbers & Electronic Configuration - JEE MCQ

Valence unpaired electrons are in 3p

Valence unpaired electrons are in 3p. 

Thus, (d).

Given a set of quantum numbers, n=2,l=0 for a multi-electron atom refers to 2s orbital. 

The next higher allowed set of 'n' and 'l' quantum numbers for this atom in the ground state is n=2,l=1. This corresponds to 2p orbital.

Note: The orbital with a higher value of the sum (n+l) has higher energy.

For 2s orbital (n+l)=(2+0)=2

For 2p orbital (n+l)=(2+1)=3

Radial nodes = (n - l - 1)
Angular nodes = l, total nodes = (n - 1), nodal plane = l

By Aufbau rule, smaller the value of (n + I), smaller the energy. If (n + I) is same for two or more orbits, suborbit with lower value of n, has smaller energy.

EC of Cr (24) is

4l -orbital 
Thus, n = 4, l = 3
m, (anyone) = - 3, - 2, - 1, 0, +1, + 2, + 3

 

(a) Three-dimensional shape of orbital is derived from angular quantum number: True
(d) Spin of the electron is derived from spin quantum number: True

Nuclear charge is defined as the net positive charge experienced by an electron in the orbital of a multi-electron atom. The closer the orbital, the greater is the nuclear charge experienced by the electrons in it.

Since 3p is closer to nucleus than 3d so it will experience greater Z

Hence C

(a) 2s (b) 2 p (c) 3d (d) 3d
Thus, (c) and (d), both 3d, have equal energy.

(a) Cr (24) = [Ar] 4s¹3d⁵ Correct
(b) K = 1s²2s²2 p⁶3s²3p⁶4s¹

(c) p-suborbit has three orbitals, each orbital can have maximum of two electrons thus, correct.
(d) s-suborbit has one orbital and this orbital can have maximum of two electrons thus, correct.

When the wave function for an atom is solved using the Schrodinger Wave Equation, the solutions obtained are called the Quantum Number which are basically n, l and m.

 The principal quantum number, n, gives the shell to which the electron belongs. The energy of the shell is dependent on ‘n’.

(i) Orbital angular momentum L = 
L depends on the value of l (azimuthal quantum number)
(ii) To describe wave function (), n, I and m are needed, if, it obeys Pauli's exclusion principle, then s is also needed.
(iii) Value of n, I and m are needed to determine size, shape and orientation.
(iv) Probability density (²) is based on n, I and m

MO configuration of O₂⁺ (8+8-1=15)


 

(9) n = 3 can have suborbits

Total nine electrons.