(a) (i) Cr2O72-+ 2OH- → 2CrO42-+ H2O
(ii) MnO4- + 4H+ +3e-→ MnO2+ 2H2O
(b) (i) Zn is not considered a transition metal because it has fully filled d orbitals.
(ii) This is due to smaller ionic sizes / higher ionic charge and availability of d orbitals that transition metals form a large no. of complexes
(iii) The E0 value for the Mn3+/ Mn2+ couple is much more positive than that for the Cr3+/ Cr2+ couple because Mn2+ is more stable (3d5) than Mn3+(3d4). And Cr3+ is more stable due to t2g3/d3 configuration.
Atomic/ionic radii does not show much variation / +3 is the most common oxidation state, in few cases +2 & +4. Atomic / ionic radii show much variation/Besides +3 oxidation state they exhibit +4,+5,+6,+7 also.
They are quite reactive. Highly reactive in finely divided state.
(ii) Cerium (Ce+4)
(iii) MnO4- + 8H+ + 5e-→ Mn2++4H2O
(iv) Mn3+ is more paramagnetic because Mn3+ has 4 unpaired electrons (3d4) therefore more paramagnetic whereas Cr3+ has 3 unpaired electrons (3d3)
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