1.

Equivalent mass of a substance may be calculated as, Equivalent mass`=("Molecular mass")/("n-factor")=("Atomic mass")/(n-factor")` n-factor= Basicity of acid or acidity of base n-factor= Number of moles of electrons gainted or lost per mole of oxidising or reducing agents n-factor= Total positive or negative valency of a salt n-factor= Valency of an ion. Concept of n-factor is very important for redox as well as for non-redox reactions. `BrO_(3)^(-)` ion reacts with `Br^(-)` to form `Br_(2)`, in acid medium. The equivalent mass of `Br_(2)` in this reaction is :A. `(4 M.w.)/(6)`B. `(3M.w.)/(5)`C. `(5M.w.)/(3)`D. `(5M.w.)/(8)`

Answer» Correct Answer - B
`2BrO_(3)^(-)+12H^(+)+10e^(-) to Br_(2)+6H_(2)O " " n_(1)=10`
`2Br^(-) to Br_(2)+6e^(-) " " n_(2)=2`
n-factor`=(n_(1)xxn_(2))/(n_(1)+n_(2))=(10xx2)/(10+2)=(20)/(12)=(5)/(3)`
`E.w.=(M.w.)/(5//3)=(3M.w.)/(5)`


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