General Questions | JEE 2011 | Discussion Page

Dissolving 120 g of urea (molecular weight 60) in 1000 g of water gave a solution of density 1.15 g /mL. The molarity of the solution is

A) 1.78 M

B) 2.00M

C) 2.05M

D) 2.22 M

Option C

Molarity = Moles of solute/Volume of solution(L)

Moles of urea= $\frac{120}{60}=2$

weight of solution =weight of solvent+weight of solute=1000+120=1120g

$\Rightarrow$ Volume = $\frac{1120g}{1.15 g/mL} \times \frac{1}{1000mL/L}=0.974 L \Rightarrow Molarity=\frac{2000}{0.974}=2.05M$

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