Topic: Quantum Numbers

Level: JEE/NEET

Instructions: Choose the correct option for each question.

Q1. Which of the following quantum numbers determines the size of an orbital?

(A) Azimuthal quantum number
(B) Principal quantum number
(C) Magnetic quantum number
(D) Spin quantum number

Q2. The maximum number of electrons that can be accommodated in a shell having principal quantum number n = 3 is:

(A) 8
(B) 18
(C) 32
(D) 9

Q3. The azimuthal quantum number for a 4d orbital is:

(A) 0
(B) 1
(C) 2
(D) 3

Q4. The possible values of magnetic quantum number for an f-subshell are:

(A) 0, ±1
(B) 0, ±1, ±2
(C) 0, ±1, ±2, ±3
(D) ±1, ±2, ±3

Q5. The maximum number of electrons that can be accommodated in a subshell having l = 2 is:

(A) 2
(B) 6
(C) 10
(D) 14

Q6. Which of the following sets of quantum numbers is not possible?

(A) n = 2, l = 1, m = 0, s = +1/2
(B) n = 3, l = 2, m = −2, s = −1/2
(C) n = 2, l = 2, m = 0, s = +1/2
(D) n = 4, l = 3, m = +2, s = −1/2

Q7. The total number of orbitals in a shell having n = 4 is:

(A) 4
(B) 8
(C) 16
(D) 32

Q8. The number of orbitals present in a subshell with l = 3 is:

(A) 3
(B) 5
(C) 7
(D) 9

Q9. The maximum number of electrons that can be accommodated in the N shell is:

(A) 8
(B) 18
(C) 32
(D) 50

Q10. Which of the following subshells does not exist?

(A) 2s
(B) 2p
(C) 2d
(D) 3d

Q11. The number of radial nodes in a 3p orbital is:

(A) 0
(B) 1
(C) 2
(D) 3

Q12. The number of angular nodes in a 4d orbital is:

(A) 0
(B) 1
(C) 2
(D) 3

Q13. The total number of nodes in a 3s orbital is:

(A) 0
(B) 1
(C) 2
(D) 3

Q14. The maximum number of electrons having the same values of n = 3 and l = 1 is:

(A) 2
(B) 6
(C) 10
(D) 14

Q15. Which of the following orbitals has the highest value of azimuthal quantum number?

(A) 3s
(B) 3p
(C) 3d
(D) 4f

Q16. The number of possible values of magnetic quantum number for l = 2 is:

(A) 2
(B) 3
(C) 5
(D) 7

Q17. The spin quantum number of an electron can have which of the following values?

(A) Only +1/2
(B) Only −1/2
(C) +1/2 or −1/2
(D) 0 or 1

Q18. The maximum number of electrons that can be accommodated in the 4f subshell is:

(A) 6
(B) 10
(C) 14
(D) 18

Q19. How many orbitals are possible for n = 3 and l = 2?

(A) 3
(B) 5
(C) 7
(D) 9

Q20. The number of orbitals having n = 4 and magnetic quantum number m = 0 is:

(A) 1
(B) 2
(C) 3
(D) 4

---

Important Formulas Related to Quantum Numbers

1. Maximum number of electrons in a shell = 2n²
2. Number of orbitals in a shell = n²
3. Number of orbitals in a subshell = 2l + 1
4. Maximum number of electrons in a subshell = 2(2l + 1)
5. Total number of nodes = n − 1
6. Number of radial nodes = n − l − 1
7. Number of angular nodes = l

Answer Key – 20 MCQs on Quantum Numbers

Question	Answer
Q1	(B)
Q2	(B)
Q3	(C)
Q4	(C)
Q5	(C)
Q6	(C)
Q7	(C)
Q8	(C)
Q9	(C)
Q10	(C)
Q11	(B)
Q12	(C)
Q13	(C)
Q14	(B)
Q15	(D)
Q16	(C)
Q17	(C)
Q18	(C)
Q19	(B)
Q20	(D)

Note: Q20 has four possible orbitals: 4s, 4p, 4d and 4f, each having one orbital with \(m_l=0\).