MCQ
An organic compound contains $49.3\%$ carbon $6.84\%$ hydrogen and its vapour density is $73$. Molecular formula of the compound is
  • A
    ${C_3}{H_5}{O_2}$
  • ${C_6}{H_{10}}{O_4}$
  • C
    ${C_3}{H_{10}}{O_2}$
  • D
    ${C_4}{H_{10}}{O_2}$

Answer

Correct option: B.
${C_6}{H_{10}}{O_4}$
b
(b)

Elements No. of Moles Simple ratio
$C = 12$ $49.3/12 = 4.1$ $4.1/2.7 = 13  \times  2 = 2.6 = 3$
$H = 1$ $6.84/1 = 6.84$ $6.84/2.7 = 2.5 \times  2 = 5$
$O = 16$ $43.86/16 = 2.7$ $2.7/2.7 = 1  \times  2 = 2$

Empirical formula = ${C_3}{H_5}{O_2}$

E.F. wt. = $12 \times 3 + 1 \times 5 + 16 \times 2 = 73$

Molecular wt = $V.D. \times 2 = 73 \times 2 = 146$

$n = \frac{{M.wt}}{{E.F.wt}} = \frac{{146}}{{73}} = 2$

Molecular formula $= (E.F)n = {({C_3}{H_5}{O_2})_2} = {C_6}{H_{10}}{O_4}$.

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