Which among the following elements is a soft element as compared to others?

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 has the maximum number of unpaired electrons?

Which of the following compounds is coloured?

Which of the following statements is correct?

Which of the following pairs of elements have one electron in the $5d$-subshell in their observed electronic configuration?