Which of the following ions has the highest magnetic moment?

Which of the following metals does not show variable valency?

Assertion : Transition metals show variable valency.
Reason : Transition metals have a large energy difference between the $ns^2$ and $(n-1)d$ electrons.

Which of the following is the general electronic configuration of transition elements?

Which of the following ions exhibit the same value of spin-only magnetic moment? $(A)$ $Ti^{3+}$, $(B)$ $Cr^{3+}$, $(C)$ $Mn^{2+}$, $(D)$ $Fe^{3+}$, $(E)$ $Sc^{3+}$. Choose the most appropriate answer from the options given below.

The outer electronic configuration of $Gd \ (At. \ No. \ 64)$ is