Which element is named after the name of a planet?

In the modern periodic table,which elements represent the transition between the most electropositive and the least electropositive elements?

Assertion : $E^o$ for $Mn^{3+}/Mn^{2+}$ is more positive than $Cr^{3+}/Cr^{2+}$.
Reason : The third ionization energy of $Mn$ is larger than that of $Cr$.

The most abundant transition metal in the earth's crust is

In which of the following transition metal ions is $d-d$ transition possible?

Calculate the 'spin only' magnetic moment of $M^{2+}_{(aq)}$ ion $(Z=27)$.