Equivalent weight of `H_3PO_2` (molecular weight=M) when it disproportionates into `PH_3` and `H_3PO_3` is

Options

A. `M`
B. `M//2`
C. `M//4`
D. `3M//4`

Answer

D

Explanation

The reaction involved is, `3H_x overset(+1)(P)O_2 The number of electrons transferred in oxidation half reaction is 4 and in the reduction half reaction is 2. Hence, the effective number of electrons transferred=4, and total number of moles involved=3. Therefore,
Equivalent Weight = `("Molecular weight")/("n factor") = M/(4//3) = (3M)/(4)`