Which of the following types of metals make the most efficient catalysts?

Gadolinium (atomic number $= 64$) is a member of the $4f$ series. Its electronic configuration in the $+3$ oxidation state is $[Xe] 4f^7$. What is the ground state electronic configuration of gadolinium?

The number of unpaired electrons in chromic ion $(Cr^{3+})$ is (atomic number of $Cr = 24$)

Which of the following ions has the highest magnetic moment value?

Which of the following is not correct about transition metals?

Given below are two statements:
Statement $I$: Ferromagnetism is considered as an extreme form of paramagnetism.
Statement $II$: The number of unpaired electrons in a $Cr^{2+}$ ion $(Z=24)$ is the same as that of a $Nd^{3+}$ ion $(Z=60)$.
In the light of the above statements,choose the correct answer from the options given below: