`Cu_(2)S` and `M_(2)S` are isomorphous. Percent weight of sulphur in `Cu_(2)S` is 20.14 and in `M_(2)S` is 12.9. if the atomic mass of Cu is 63.5, Calculate that of the other metal,M.

Explanation

`Cu_(2)S` contain 20.14% S and 79.86% Cu
Weight of Cu that combines with 1 g of S `=(79.86)/(20.14)=3.965g`
`M_(2)S` contains 12.9% S and 87.1% M
Weight of M that combines with 1g of S =`(87.1)/(12.9)=6.765g`
From law of isomorphism , (since valency of two metals is same )
` ("atomic mass of M ")/("atomic mass of Cu")=("Weight of M")/("weight of Cu")`
Atomic mass of M `=(6.752)/(3.965)xx63.5=108`