c
Option \(1)\) Manganate \(\Rightarrow MnO _{4}^{2-}\)

Permanganate \(\Rightarrow MnO _{4}^{-}\)

\(2 \times 2 P _{\pi}-3 d _{\pi}\)

\(1 \times 2 P _{\pi}-4 P _{\pi}\)

\((2)\) \(MnO _{4}^{2-} \Rightarrow\) green

\(MnO _{\stackrel -4} \Rightarrow\) purple/violet

\((3)\) Manganate contains \(1\) unpaired electron hence it is paramagnetic

where as permanganetic contains no unpaired electrons hence it is diamagnetic.

\((4)\) Both have d's hybridisation hence both have tetrahedral geometry.