Answer
$T=0.48 \mathrm{~K} .$
Work Step by Step
Let the,
$$
K=\frac{3}{2} k T=\mid \vec{\mu} \cdot \vec{B}-(|-\vec{\mu} \cdot \vec{B}| \mid=\\2 \mu B
$$
Now which leads to,
$$
T=\frac{4 \mu B}{3 k}=\frac{4\left\{1.0 \times 10^{-23} \mathrm{~J} / \mathrm{T}||_{0.50 \mathrm{~T}}\right\}}{3\left\{1.38 \times 10^{-23} \mathrm{~J} / \mathrm{K} \|\right.}\\=0.48 \mathrm{~K} .
$$
