At PH = 4,  exists As:

In acidic medium H₂O₂ changes K₂Cr₂O₇ to CrO₅ (deep violet solution in ether) having two peroxy linkage. Oxidation number of Cr in CrO₅ is:

Hg­₂Cl₂ ionises as ……... and cation has ……… unpaired electron (s).

Transition metals form alloys easily. The reason for this is

An inorganic compound on strong heating gave a blackish brown powder and two oxides of sulphur. The powder was dissolved in HCl when a yellow solution was obtained which gave a blood red coloured solution with thiocyanide ions. The inorganic compound may be

The species that undergoes disproprotionation in an alkaline medium are

In industrial smog, Cu corrodes to