Question

a) Which of the following is an impossible set of quantum numbers for an electron in an atom? These are in the order n, l, m_l, and m_s.

A.   3, 2, 1, +1/2              B. 3, 1, 0, –1/2           C. 3, 1, –1, –1/2     D. 3, 3, 2, +1/2

b) Which of the following electronic transitions could lead to the emission of light from an atom?

A.   1s → 4p          B. 4p → 3d         C. 3d → 4f           D.   2p → 3s

Answer 1

Q.No-(a)

Correct answer is D

We know

Azimuthal Quantum number, l = 0 to n-1

Where n is principal Quantum number

ml is magnetic Quantum number = -l , 0 , +L

ms is spin Quantum number +1/2 or -1/2

In option D

n = 3 then L should be 0 to 3-1 or 0 to means l = 0,1,2

Value of l = 3 is not possible for n= 3

(b) Answer is D

Light is emitted when an electron falls from a higher energy orbit to a lower energy orbit.

Energy of 2p = 2+1=3 (According to n+l rule)

Energy of 3s = 3+0 =3

Since n+L is same for both 2p and 3s.But according to energy level order to filling the electronic configuration is 2p3s