MCQ
Molality of an aqueous solution of urea is $4.44 \mathrm{~m}$. Mole fraction of urea in solution is $x \times 10^{-5}$. Value of $x$ is. . . . . . (integer answer)
- A$70$
- B$73$
- ✓$74$
- D$80$
✓
Answer
Correct option: C.
$74$
c
Molality of urea is $4.44 \mathrm{~m}$, that means $4.44$ moles of urea present in $1000 \mathrm{gm}$ of water.
Molality of urea is $4.44 \mathrm{~m}$, that means $4.44$ moles of urea present in $1000 \mathrm{gm}$ of water.
$\therefore \mathrm{X}_{\text {urea }}=\frac{4.44}{4.44+\frac{1000}{18}}$
$=0.0740$
$74 \times 10^{-3}$
$\mathrm{X}=74$
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