JEE Main · 2023 · 06 Apr 2023 · Shift 1 · Solutions

Mass of Urea (

NH_{2} CONH_{2}

) required to be dissolved in 1000 g of water to reduce the vapour pressure of water by

25%

is......g. (Nearest integer)

Given: Molar mass of N, C, O and H are 14, 12, 16 and 1 g

mol^{- 1}

respectively.

Answer: 1111

Solution

Reducing the vapour pressure of water by 25 percent means

P_{s} = 0.75 P^{0}

, so the relative lowering is

\frac{P ^{0} - P _{s}}{P _{s}} = \frac{0.25}{0.75} = \frac{1}{3}

, which equals the mole ratio of solute to solvent. The molar mass of urea is

2 (14) + 12 + 16 + 4 (1) = 60 g mo l^{- 1}

and the water provides

\frac{1000}{18}

mol. Writing

\frac{1}{3} = \frac{x /60}{1000/18}

gives

x = \frac{60000}{54} = 1111.1 g

. The mass of urea required is 1111 g.

JEE Main · 2023 · 06 Apr 2023 · Shift 1 · Integer answer

Practise more: all JEE Main PYQs on Solutions →

More JEE Main questions on Solutions

Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and $PQ_{2}$ . When 1 g of PQ is dissolved in 50 g of solvent 'A', $Δ T_{b}$ was 1.176 K while when 1 g of $PQ_{2}$ is dissolved in 50 g of solvent 'A', …
JEE Main 2026View solution →
Consider a solution of $CO_{2} (g)$ dissolved in water in a closed container.

Which one of the following plots correctly represents variation of log (partial pressure of CO2 in vapour phase above water) [y-axis] with log (mole fraction of $CO_{2}$ …
JEE Main 2026View solution →
Given below are two statements:

Statement I: The Henry's law constant $K_{H}$ is constant with respect to variations in solution's concentration over the range for which the solutions is ideally dilute.
Statement II : $K_{H}$ does not diff …
JEE Main 2026View solution →
The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is $____$ $g L^{- 1}$ . (Nearest integer)

Given: …
JEE Main 2026View solution →
A substance 'X' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass $= 300 g mol^{- 1}$ ) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent 'Y' is $____$ $\times 1 0^{- 2}$ . (Nearest integer)
[Giv …
JEE Main 2026View solution →
Which one of the following graphs accurately represents the plot of partial pressure of $CS_{2}$ vs its mole fraction in a mixture of acetone and $CS_{2}$ at constant temperature ?
JEE Main 2026View solution →