MHT CET · Chemistry · Solutions

An aqueous solution of urea containing \(18 \mathrm{~g}\) urea in \(1500 \mathrm{~cm}^{3}\) of the solution has a density equal to \(1.052\). If the molecular weight of urea is 60, the molality of the solution is

A \(0.200\)
B \(0.192\)
C \(0.100\)
D \(1.200\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(0.192\)

Step-by-step Solution

Detailed explanation

\(
1500 \mathrm{cc} \text { . solution }=1500 \times 1.052 \mathrm{~g}
\)
\(=1578 \mathrm{~g}\)
Weight of solvent \(=1560 \mathrm{~g}\)
Weight of solute \(=18 \mathrm{~g}\)
Molality \(=\frac{\text { weight of solute }}{\text { molecular weight of solute } \times}\)
weight of solvent in \(\mathrm{kg}\)
\(=\frac{18 \times 1000}{60 \times 1560}\)
\(=0.192 \mathrm{~m}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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