Pick out the correct statements from the following. (I) Cobalt (III) is more stable in octahedral complexes. (II) Zinc froms coloured ion or complexes. (III) Most of the d-block elements and their compounds are ferromagnetic. (IV) Osmium show (VIII) oxidation sate.

Pick out the correct statements from the following. (I) Cobalt (III) i

1.	Pick out the correct statements from the following. (I) Cobalt (III) is more stable in octahedral complexes. (II) Zinc froms coloured ion or complexes. (III) Most of the d-block elements and their compounds are ferromagnetic. (IV) Osmium show (VIII) oxidation sate.
Answer» I and II I and III II andIV I and IV Solution :(I) `Co^(3+)` have higher charge density than `Co^(2+), So Co^(3+)` is more stable in octahedral COMPLEXES. (II) Zn exhibits only `+2` oxidation STATE.So, `Zn^(2+)=[Ar]3d^(10),4s^(0)` Since, iy does not contain any unpaired electron, its compounds are colourless. (III) d-block elements are generally paramagnetic and sometime DIAMAGNETIC , but not ferromagnetic. (IV) OSMIUM and ruthenium are VIII group elements, so can exibit the highest oxidation state`+8` in their oxides, HENCE, statements I and IV are correct.