Ionisation enthalpies of $Ce,\,Pr$ and $Nd$ are higher than $Th,\,Pa$ and $U$. Why ?

Which of the following electronic configuration would be associated with the highest magnetic moment?

$F{e^{2 + }}$ shows

Chloride of which of the following element is coloured

Metals generally melt at very high temperature. Amongst the following, the metal with the highest melting point will be $......$

The number of hydrogen bonded water molecule(s) associated with $CuSO_4\cdot 5H_2O$ is