NEET 2026
- Exam
- NEET
- Year
- 2026
- Subject
- Chemistry
- Chapter
- Chapter
NEET 2026 · Chemistry · Chapter
Assertion (A): Oxygen molecule ( O_2 ) is paramagnetic in nature....
Assertion (A): Oxygen molecule () is paramagnetic in nature.
Reason (R): The molecular orbital electronic configuration of contains two unpaired electrons in its bonding molecular orbitals.
Reason (R): The molecular orbital electronic configuration of contains two unpaired electrons in its bonding molecular orbitals.
Options
- ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- CAssertion (A) is true but Reason (R) is false.
- DBoth Assertion (A) and Reason (R) are false.
Correct answer
C. Assertion (A) is true but Reason (R) is false.
Step-by-step solution
The total number of electrons in molecule is .
The molecular orbital electronic configuration of is \sigma_{1s}^{2} \sigma^{*}_{1s}^{2} \sigma_{2s}^{2} \sigma^{*}_{2s}^{2} \sigma_{2p_z}^{2} \pi_{2p_x}^{2} = \pi_{2p_y}^{2} \pi^{*}_{2p_x}^{1} = \pi^{*}_{2p_y}^{1}.
Due to the presence of two unpaired electrons, is paramagnetic in nature. Thus, Assertion (A) is true.
The two unpaired electrons are present in the antibonding molecular orbitals ( and ), not in bonding molecular orbitals. Thus, Reason (R) is false.
Answer: Assertion (A) is true but Reason (R) is false.
The molecular orbital electronic configuration of is \sigma_{1s}^{2} \sigma^{*}_{1s}^{2} \sigma_{2s}^{2} \sigma^{*}_{2s}^{2} \sigma_{2p_z}^{2} \pi_{2p_x}^{2} = \pi_{2p_y}^{2} \pi^{*}_{2p_x}^{1} = \pi^{*}_{2p_y}^{1}.
Due to the presence of two unpaired electrons, is paramagnetic in nature. Thus, Assertion (A) is true.
The two unpaired electrons are present in the antibonding molecular orbitals ( and ), not in bonding molecular orbitals. Thus, Reason (R) is false.
Answer: Assertion (A) is true but Reason (R) is false.