NEETChemistryStructure of Atom
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Cr ²⁺ and Fe ²⁺ ions have the same spin-only magnetic moment. Reason (R): Both Cr ²⁺ and Fe ²⁺ ions have the same number of electrons in their 3d subshell. In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is false but (R) is true
- D(A) is true but (R) is false
Correct answer
D. (A) is true but (R) is false
Step-by-step solution
Assertion (A) is true: The ground state electronic configuration of Cr is [ Ar ] 4s^1 3d^5 . Removing two electrons gives Cr ²⁺ with a configuration of [ Ar ] 3d^4 , which has 4 unpaired electrons ( n=4 ). The ground state electronic configuration of Fe is [ Ar ] 4s^2 3d^6 . Removing two electrons gives Fe ²⁺ with a configuration of [ Ar ] 3d^6 , which also has 4 unpaired electrons ( n=4 ). Since both ions have the same number of unpaired electrons ( n=4 ), they have the same spin-only magnetic moment ( = 4(4+2) =