Question

Arrange the following in increasing order of spin only magnetic movement: (A) $Co^{2+}$, (B) $Ti^{3+}$, (C) $Ti^{2+}$, (D) $Fe^{2+}$, (E) $Sc^{3+}$}

• A. E $<$ C $<$ B $<$ A $<$ D
• B. E $<$ B $<$ C $<$ A $<$ D
• C. E $<$ B $<$ A $<$ C $<$ D
• D. E $<$ A $<$ B $<$ C $<$ D

Hint:

Just count the unpaired electrons! For $d^1$ to $d^5$, $n$ is the number of electrons; for $d^6$ to $d^9$, $n$ is (10 - number of electrons).

Answer 1

The Correct Option is B

Step 1: Concept Spin-only magnetic moment ($\mu$) is calculated using the formula $\mu = \sqrt{n(n+2)}$ BM, where $n$ is the number of unpaired electrons. Higher $n$ results in a higher magnetic moment.

Step 2: Meaning We must determine the number of unpaired electrons for each ion: $Sc^{3+}$ ($d^0, n=0$), $Ti^{3+}$ ($d^1, n=1$), $Ti^{2+}$ ($d^2, n=2$), $Co^{2+}$ ($d^7, n=3$), and $Fe^{2+}$ ($d^6, n=4$).

Step 3: Analysis Ranking based on $n$: $Sc^{3+}$ (0) $<$ $Ti^{3+}$ (1) $<$ $Ti^{2+}$ (2) $<$ $Co^{2+}$ (3) $<$ $Fe^{2+}$ (4).

Step 4: Conclusion The increasing order of magnetic moment is E $<$ B $<$ C $<$ A $<$ D. Final Answer: (B)