⇒Transition and Inner Transition Elements

Correct Option is (B)

$\begin{array}{rl}& \mathrm{Cu}(\mathrm{Z}=29):[\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^1\\ & {\mathrm{Cu}}^{2+}:[\mathrm{Ar}]3{\mathrm{d}}^9\\ & \text{ No. of unpaired }{\mathrm{e}}^{-}=1\\ & \mu =\sqrt{\mathrm{n}(\mathrm{n}+2)}=\sqrt{1(1+2)}=\sqrt{3}=1.73\mathrm{BM}\end{array}$

Since the number of unpaired electrons $(\mathrm{n})=1,\mu \approx 2$. Hence, option (B) is the correct answer.

Correct Option is (D)

	Ions	Outer shell electronic configuration	No. of unpaired electrons
(A)	${\mathrm{Cr}}^{3+}$	$3{\mathrm{d}}^3$	3
(B)	${\mathrm{V}}^{3+}$	$3{\mathrm{d}}^2$	2
(C)	${\mathrm{Ti}}^{3+}$	$3{\mathrm{d}}^1$	1
(D)	${\mathrm{Sc}}^{3+}$	$3{\mathrm{d}}^0$	0

${\mathrm{Sc}}^{3+}$ is does not exhibit spin-only magnetic moment because of the absence of unpaired electrons.

Correct Option is (B)

$\begin{array}{rl}& {\mathrm{Cr}}^{2+}:[\mathrm{Ar}]3{\mathrm{d}}^4\Rightarrow \mathrm{n}=4\\ & \begin{array}{rl}& \therefore \text{ Spin-only magnetic moment, }\\ & \mu =\sqrt{\mathrm{n}(\mathrm{n}+2)}\mathrm{BM}\\ & =\sqrt{4(4+2)}=\sqrt{24}\mathrm{BM}\\ & =4.90\mathrm{BM}\end{array}\end{array}$

Since the number of unpaired electrons (n) = 4, $\mu \approx 5$. Hence, option (B) is the correct answer.

Correct Option is (A)

Among the options provided, the element that is ferromagnetic is :

• Option A - Ni (Nickel)

Nickel is a ferromagnetic material, along with iron and cobalt. These elements are characterized by their ability to be magnetized and to maintain a magnetic field.

The other options are not ferromagnetic :

• Option B - Cu (Copper) : Copper is not ferromagnetic. It is, in fact, diamagnetic, meaning it is weakly repelled by magnetic fields.




• Option C - Sc (Scandium) : Scandium is not ferromagnetic. Like copper, it is also classified as diamagnetic.




• Option D - Zn (Zinc) : Zinc is not ferromagnetic. It is another example of a diamagnetic material.

Ferromagnetic materials are unique in their ability to retain a magnetic field after an external magnetic field is removed, a property not found in the other elements listed here.