1.

A solution containing 25.6 g of sulphur dissolved in 1000 g of naphthanlene whose melting point is `80.1^(@)C`, gave a freezing point lowering of `0.68^(@)C`. Calculate the formula of sulphur. `K_(f)` for naphthanlene is 6.8 K/m.

Answer» Correct Answer - `S_(8)`
`W_(B)=25.6g, W_(A)=1 kg, DeltaT_(f)=0.68K, K_(f)=6.8" k kg mol"^(-1)`
`M_(B)=(K_(f)xxW_(B))/(DeltaT_(f)xxW_(A))=((6.8" K kg mol"^(-1))xx(25.6 g))/((0.68K)xx(1kg))=256" g mol"^(-1)`
`"Atomicity of sulphur"=((256" g mol"^(-1)))/((32" g mol"^(-1)))=8`
`"Therefore, molecular fomula of sulphur"=S_(8)`.


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