Question

`13.4 g` of a sample of unstable hydrated salt `Na_(2)SO_(4).XH_(2)O` was found to contains `6.3 g` of `H_(2) O`. The number of molecular of water of crystalistion is
A. (a)6
B. (b)5
C. (c )7
D. (d)8

Answer 1

Correct Answer - c
`("wt. of water")/("wt. of sample")=("wt. of water in the compound")/("mol. Wt. of the compound")`
`6.3/13.4=(x xx18)/(142+18x)x=7`