Which of the following is ferromagnetic?

The number of unpaired electrons in Gadolinium $[Z = 64]$ is

Which of the following pairs has approximately the same ionic size?

Assertion: Cuprous ion $(Cu^{+})$ has unpaired electrons while cupric ion $(Cu^{2+})$ does not.
Reason: Cuprous ion $(Cu^{+})$ is colourless whereas cupric ion $(Cu^{2+})$ is blue in the aqueous solution.

The spin-only magnetic moment value of $M^{3+}$ ion (in gaseous state) from the pairs $Cr^{3+}/Cr^{2+}$,$Mn^{3+}/Mn^{2+}$,$Fe^{3+}/Fe^{2+}$,and $Co^{3+}/Co^{2+}$ that has a negative standard electrode potential,is $B.M.$ (Nearest integer).

Misch metal is an alloy of $:-$