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KCET · Chemistry · Some Basic Concepts of Chemistry

The empirical formula of a non-electrolyte is \(\mathrm{CH}_{2} \mathrm{O}\). A solution containing \(6 \mathrm{~g}\) of the compound exerts the same osmotic pressure as that of \(0.05 \mathrm{M}\) glucose solution at the same temperature. The molecular formula of the compound is

  1. A \(\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{2}\)
  2. B \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{3}\)
  3. C \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}_{5}\)
  4. D \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{4}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{4}\)

Step-by-step Solution

Detailed explanation

Solutions having same osmotic pressure, at a given temperature, have same concentration. Concentration of compound \(=\) concentration of glucose
\[
\begin{aligned}
&\frac{6}{\mathrm{M} \times 1}=0.05 \\
&\mathrm{M}=\frac{6}{0.05}=120 \\
&\text { Empirical formula mass }\left(\mathrm{CH}_{2} \mathrm{O}\right)=12+2+16 \\
&\mathrm{n}=\frac{\text { molecular mass }}{\text { empirical formula mass }} \\
&=\frac{120}{30}=4
\end{aligned}
\]
Hence, molecular formula \(=\left(\mathrm{CH}_{2} \mathrm{O}\right)_{4}=\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{4}\)