JEE Main 2022 · 27 July · morning · Single correct · +4 / −1
Given below are two statements.
Statement I: O₂, Cu²⁺, and Fe³⁺ are weakly attracted by magnetic field and are magnetized in the same direction as magnetic field.
Statement II: NaCl and H₂ O are weakly magnetized in opposite direction to magnetic field.
In the light of the above statements, choose the most appropriate answer from the options given below.
- (a) Both Statement I and Statement II are correct.
- (b) Both Statement I and Statement II are incorrect.
- (c) Statement I is correct but Statement II is incorrect.
- (d) Statement I is incorrect but Statement II is correct.
Answer and solution
Answer (a) Both Statement I and Statement II are correct.
Solution
Chemistry ma’am · 3 steps
Count unpaired electrons: any unpaired means paramagnetic, all paired means diamagnetic.
- Paramagnetic. A species with unpaired electrons is paramagnetic. It is weakly attracted into a magnetic field and is magnetized in the same direction as the field.
- Diamagnetic. A species with all electrons paired is diamagnetic. It is weakly repelled and is magnetized in the direction opposite to the field.
Species Electron picture Unpaired electrons Behaviour O₂ MO theory: one electron in each π^*2p orbital 2 paramagnetic Cu²⁺ [Ar] 3d⁹ 1 paramagnetic Fe³⁺ [Ar] 3d⁵ 5 paramagnetic NaCl Na⁺ is [Ne], Cl⁻ is [Ar] 0 diamagnetic H₂O 10 electrons, all in bonding or lone pairs 0 diamagnetic - So. Statement I describes paramagnetism and Statement II describes diamagnetism, and each matches its species. Both statements are correct, so the answer is (a).
The idea to keep. Write the configuration and look for unpaired electrons. Unpaired means drawn in, along the field. All paired means pushed out, opposite to the field. For O₂, always use MO theory.
Answer from the NTA final answer key. Solution by PrepWiser.