JEE Main · 2022 · 29 Jun 2022 · Shift 2 · Solutions

WhatsApp Email

Elevation in boiling point for 1.5 molal solution of glucose in water is 4 K . The depression in freezing point for 4.5 molal solution of glucose in water is 4 K . The ratio of molal elevation constant to molal depression constant

(K_{b} / K_{f})

is ____ .

Answer: 3

Solution

Using the colligative property equations:

For boiling point elevation:

Δ T_{b} = i K_{b} m

4 = 1 \times K_{b} \times 1.5

K_{b} = \frac{4}{1.5}

For freezing point depression:

Δ T_{f} = i K_{f} m

4 = 1 \times K_{f} \times 4.5

K_{f} = \frac{4}{4.5}

Taking the ratio:

\frac{K _{b}}{K _{f}} = \frac{4/1.5}{4/4.5} = \frac{4}{1.5} \times \frac{4.5}{4} = \frac{4.5}{1.5} = 3

Therefore, the answer is 3.

JEE Main · 2022 · 29 Jun 2022 · Shift 2 · 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 →