The crystalline salt `Na_(2)SO_(4).xH_(2)O` on heating loses 55.9 % of its weight. The formula of the crystalline salt is

Options

A. `Na_(2)SO_(4).5H_(2)O`
B. `Na_(2)SO_(4).7H_(2)O`
C. `Na_(2)SO_(4).2H_(2)O`
D. `Na_(2)SO_(4).10H_(2)O`

Answer

D

Explanation

44.1 g anhydrous `Na_(2)SO_(4)` are associated with `H_(2)O=55.9g`
Molar mass of anhyd. `Na_(2)SO_(4)`
`=2xx23+32+4xx16`
`=142g`
`therefore "142 g of anhyd. "Na_(2)SO_(4)` will be associated with
`H_(2)O=(55.9)/(44.1)xx142g=180g="10 moles of "H_(2)O`