Question

Assertion : Magnetic moment of $Mn^{2+}$ is less than that of $Cr^{2+}$.
Reason : Higher the atomic number smaller is the magnetic moment.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (D)

The magnetic moment is determined by number of unpaired electrons and is calculated by using the formula, $\mu = \sqrt{n\left(n+2\right)}$ where n is number of unpaired electrons.
It increases with increase in number of unpaired electrons hence $Mn^{2+}$ will have higher magnetic moment than $Cr^{2+}$.