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Question
A compound made up of two elements X and Y has an empirical formula X2Y. If the atomic weight of X is 10 and that of Y is 5 and the compound ha a vapor density 25, find its molecular formula.
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Solution
Empirical formula = X2Y
Atomic Weight (X) = 10
Atomic Weight (Y) = 5
Empirical Formula Weght = 2 × 10 + 5 = 25
So, n = `"Molecular weight"/"Empirical formula weight" = (2xx"V.D")/"Empirical formula weight"`
`n = (2 xx 25)/25 = 2`
So Molecular Formula = (X2Y) × 2 = X4Y2
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