Which of the following pairs of ions are colourless?

Which of the following series of transition metal ions has a $3d^2$ electronic configuration?

What is the general electronic configuration for the $2^{nd}$ row transition series?

Which of the following statements are correct about $Zn, Cd$ and $Hg$?
$A$. They exhibit high enthalpy of atomization as the d-subshell is full.
$B$. $Zn$ and $Cd$ do not show variable oxidation state while $Hg$ shows $+I$ and $+II$.
$C$. Compounds of $Zn, Cd$ and $Hg$ are paramagnetic in nature.
$D$. $Zn, Cd$ and $Hg$ are called soft metals.
Choose the most appropriate from the options given below:

$Cr^{2+}$ has a magnetic moment same as that of

The general electronic configuration of transition elements is