Besides $Zn$ and $Cu$,german silver contains the metal

Why is the $E^{\Theta }$ value for the $Mn^{3+}/Mn^{2+}$ couple much more positive than that for $Cr^{3+}/Cr^{2+}$ or $Fe^{3+}/Fe^{2+}$? Explain.

Number of unpaired electrons in $Mn^{2+}$ is

The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?

Number of paramagnetic ions among the following $d$- and $f$-block metal ions is . . . . . . . $Mn^{2+}$,$Cu^{2+}$,$Zn^{2+}$,$Yb^{2+}$,$Sc^{3+}$,$La^{3+}$,$Gd^{3+}$,$Lu^{3+}$,$Ti^{4+}$,$Ce^{4+}$. (Atomic number of $Mn = 25$,$Cu = 29$,$Zn = 30$,$Yb = 70$,$Sc = 21$,$La = 57$,$Gd = 64$,$Lu = 71$,$Ti = 22$,$Ce = 58$)

Which of the following has second ionisation potential less than expected?