A pure gas that is `14.3%` hydrogen and `85.7%` carbon by mass has a density of `2.5g L^(-1)` at `0^(@)C` and 1 atm pressure. What is the molecular formula of the gas :

Options

A. `CH_(2)`
B. `C_(2)H_(4)`
C. `C_(4)H_(8)`
D. `C_(6)H_(12)`

Answer

C

Explanation

`% "mol Simples ratio"`
`C" " 85.7 " "85.7//12 = 7.14" "7.14// 7.14 = 1 " "1`
`H " "14.3" " 14.3//1 = 14.3" " 14.3//7.14 = 2 " "2`
`:.` Emperical formal `=CH_(2)`
`:. PMw = DRT`
`Mw = (DRT)/(P) = (2.5 xx 0821 xx 273)/(1) =56`
`n = ("molecular wt")/("Ewt") = (56)/(14) = 4`
Molecular formula `= n xx E.F`
`= 4 xx CH_(2)`
`= C_(4) H_(8)` .