If `alpha` is the degrcc of dissociation of `Na_(2) SO_(4)` the Vant Hoff s factor (i) uscd for calculating the molecular mass is

Options

A. `1+ alpha `
B. `1- alpha`
C. `1+ 2 alpha`
D. `1- 2 alpha `

Answer

D

Explanation

`Na_(2) SO_(4) to 2Na^(4)+ SO_(4)^(2-)`
`{:(" Mol. Beforre dissociation",1,0,0),("Mol after dissociation",1-alpha, 2 alpha, 1 alpha ):}`
`i =1- alpha+ 2 alpha + alpha =1+ 2 alpha `