The number of unpaired electrons in $Cr^{+}$ will be

Those elements whose two outermost orbitals are incompletely filled with electrons are known as:

Explain briefly how the $+2$ oxidation state becomes more stable in the first half of the first-row transition elements as the atomic number increases.

Metal-metal bonding is more frequent in $4d$ or $5d$ series than in $3d$ series due to

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.

Among the following transition elements,which one has the lowest first ionization energy?