1. Tardigrade
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  3. Chemistry
  4. If at certain temperature, the vapour pressure of pure water is 25 mm of Hg and that of a very dilute aqueous urea solution is 24.5 mm of Hg, the molality of solution is

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Q. If at certain temperature, the vapour pressure of pure water is $25\, mm$ of $Hg$ and that of a very dilute aqueous urea solution is $24.5\, mm$ of $Hg$, the molality of solution is

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Solution:

By using the relation, molality $=\frac{p^{\circ}-p_{s}}{p^{\circ}} \times \frac{1000}{M}$
Molality $(m)=\frac{25-24.5}{25} \times \frac{1000}{18}$
$=\frac{0.5}{25} \times \frac{1000}{18}=1.11$
$\therefore$ Molality of solution $=1.11\, m$