Give the oxidation state , d-orbital occupation and coordination number iof the central metal ion in the following complexes :
(a) `K_(3)[Co(C_(2)O_(4))_(3)]` (b) `(NH_(4))_(2)[CoF_(4)]` (c) `Cis - [CrCl_(2)(en)_(2)]Cl` (d) `[Mn(H_(2)O)_(6)]SO_(4)`

Explanation

`{:(,"Complex","Oxidation state","Coordination No.","d-orbital occupation","Unpaired electrons"),((i),K_(3)^(+)[Co(C_(2)O_(4))_(3)]^(3-),x-6=-3,6("as "C_(2)O_(4)^(2-)" is didentate"),Co^(3+)=3d^(6),0),(,,x=+3,,=t_(2g)^(6)e_(g)^(0),),((ii),(NH_(4))_(2)^(+)[CoF_(4)]^(2-),x-4=-2,4,Co^(2+)=3d^(7),3),(,,x=+2,,=e^(4)t_(2)^(3),),((iii),cis-[Cr(en)_(2)Cl_(2)]^(+)Cl^(-),x+0-2=+1,"6 (en is didentate)",Cr^(3+)=3d^(3),3),(,,x=+3,,=t_(2g)^(3),),((iv),[Mn(H_(2)O)_(6)]^(2+)SO_(4)^(2-),x+0=+2,6,Mn^(2+)=3d^(5),5),(,,x=+2,,=t_(2g)^(3)e_(g)^(2),),(,,,,,):}`