Arrange the following metal complex/ compounds in the increasing order of spin only magnetic moment. Presume all the three, high spin system.

(Atomic numbers $\mathrm{Ce}=58, \mathrm{Gd}=64$ and $\mathrm{Eu}=63$.)

(a) ${\left({\mathrm{NH}}_4\right)}_2\left[\mathrm{Ce}{\left({\mathrm{NO}}_3\right)}_6\right]$

(b) $\mathrm{Gd}{\left({\mathrm{NO}}_3\right)}_3$ and

(c) $\mathrm{Eu}{\left({\mathrm{NO}}_3\right)}_3$

• A

  $\left(\mathrm{b}\right)<\left(\mathrm{a}\right)<\left(\mathrm{c}\right)$
• B

  $\left(\mathrm{c}\right)<\left(\mathrm{a}\right)<\left(\mathrm{b}\right)$
• C

  $\left(\mathrm{a}\right)<\left(\mathrm{b}\right)<\left(\mathrm{c}\right)$
• Correct answer
  D

  $\left(\mathrm{a}\right)<\left(\mathrm{c}\right)<\left(\mathrm{b}\right)$

Hence, the correct answer is option: 'D'.