How to calculate valency factor of a species undergoing disproportionation reaction.For ex what is the v.f of hydrogen peroxide which is converting to water and oxygen.

HYDROGEN PEROXIDE GOING TO WATER AND OXYGEN..HERE ONE O ATOM AT -1 OXIDATION STATE IS GOING TO 0 AND THE OTHER ONE IS GOING TO -2 OXIDATION STATE,

NET ELECTRON EXCHANGE IS 2. HENCE VALENCY FACTOR IS ALSO 2

in this question u can also do it by d oxidation number method..the difference in electrons you get is the valency factor