Which of the following elements show $+7$ oxidation states?

The number of oxidation states exhibited by manganese $(Mn)$ is

Why are the $E^o$ values for $Mn^{2+}/Mn$,$Zn^{2+}/Zn$,and $Ni^{2+}/Ni$ more negative than expected? The table below provides the values:
| $E^o_{Mn^{2+}/Mn}$ | $E^o_{Zn^{2+}/Zn}$ | $E^o_{Ni^{2+}/Ni}$ |
| :--- | :--- | :--- |
| $-1.18 \ V$ | $-0.76 \ V$ | $-0.25 \ V$ |

Which of the following pairs of ions have the same paramagnetic moment?

The metal ion having maximum paramagnetic behaviour among the first transition series elements is,

Which one of the following has a magnetic moment of $1.75 \ BM$?