When 2.46 of hydrated salt `(MSO_(4)x H_(2)O)` is completely dehydrated, 1.20 g of anhydrous salt is obtained. It molecular weight of anhydrous salt is `120 g mol^(-1)`, the value of x is

Options

A. 2
B. 4
C. 5
D. 7

Answer

D

Explanation

2.46 g of hydrated salt `(MSO_(4).xH_(2)O)` gives anhydrous salt =1.20 g
`therefore` Mass of water `=2.46 - 1.20 = 1.26`g
Percentage of water `=1.26/2.46 xx 100 = 1.26 g`
Percentage of water `=1.26/2.46 xx 100 =51.2%`
120 (g) (1 mol) of anhydrous salt contain water
`=51.2/48.8 xx 120 = 126`g
No. of water molecules `=126/18 =7` molecules