Question

10 " mL of " a gaseous organic compound containing C, H and O only was mixed with 100 " mL of " `O_(2)` and exploded under condition which allowed the `H_(2)O` formed to condense. The volume of the gas after explosion was 90 mL. On treatment with KOH solution, a further contraction of 20 mL in volume was observed. The vapour density of the compound is 23. All volume measurements were made under the same condition.
Q.The molecular formula of the compound is
A. `C_(3)H_(6)O`
B. `C_(2)H_(4)O`
C. `C_(2)H_(6)O`
D. `C_(3)H_(8)O`

Answer 1

Correct Answer - C
`underset(10vol)underset(1vol)(C_(x)H_(y)O_(z))+underset(10(x+y//4-z//2))underset((x+y//4-z//2))((x+y//4-z//2))O_(2)rarrunderset(10x vol)underset(xvol)(xCO_(2))+(y)/(2)H_(2)O`
`10x =20` or `x = 2`
`10(x+y//4 -z//2) = (100 - 70) = 30`
or `x +y//4 - z//2 = 3` or `y//4 - z//2 =1` or
`y - 2z = 4` ...(1)
Mol. mass `= 2xx 23 = 46 +12 x +y +16z`
or `y +16z = 22` ........(2)
solving `y = 6` and `z = 1`
Formula of the compound `=C_(2)H_(6)O`