jee main chemistry important questions | Solutions jee main questions FREE

Q 31 :

The vapour pressure vs. temperature curve for a solution–solvent system is shown below:

[IMAGE 140]

The boiling point of the solvent is ______ °C. [2023]

0%

(82)

The temperature at which vapour pressure of solvent becomes 1 atm is called normal B.P. of solvent. So, the boiling point of the solvent is 82°C.

Q 32 :

If the boiling points of two solvents X and Y (having same molecular weights) are in the ratio 2 : 1 and their enthalpy of vaporization are in the ratio 1 : 2, then the boiling point elevation constant of X is m times the boiling point elevation constant of Y. The value of m is ________ (Nearest Integer) [2023]

0%

(8)

$Δ T_{b} = K_{b} m$

$K_{b} = \frac{R T_{b}^{2} \times M_{solvent}}{1000 \times Δ H_{vap}}$

$\frac{{(Δ T_{b})}_{_{X}}}{{(Δ T_{b})}_{Y}} = {[\frac{{(T_{b})}_{X}}{{(T_{b})}_{Y}}]}^{2} \times \frac{M_{X}}{M_{Y}} \times \frac{Δ H_{Y}}{Δ H_{X}} = {(\frac{2}{1})}^{2} (\frac{1}{1}) \times \frac{2}{1} = 8$

Q 33 :

An aqueous solution of volume 300 ${cm}^{3}$ contains 0.63 g of protein. The osmotic pressure of the solution at 300 K is 1.29 mbar. The molar mass of the protein is ________ g ${mol}^{- 1}$ . Given: R = 0.083 L bar $K^{- 1}$ ${mol}^{- 1}$ [2023]

0%

(40535)

$π = \frac{W / M}{V} R T$

or $M = \frac{W \times R \times T}{π \times V}$ $= \frac{0.63 \times 0.083 \times 300}{1.29 \times 10^{- 3} \times 300 \times 10^{- 3}}$

or $M = 40535 g/mol$

Q 34 :

Solutions of 12 g of non-electrolyte (A) prepared by dissolving it in 1000 mL of water exerts the same osmotic pressure as that of 0.05 M glucose solution at the same temperature. The empirical formula of A is ${CH}_{2} O$ . The molecular mass of A is ______ g. (Nearest integer) [2023]

0%

(240)

$For isotonic solutions$

$π_{1} = π_{2}$

$C_{1} = C_{2} (For non-electrolyte)$

$(\frac{12}{M_{A} \times 1}) = 0.05$

$M_{A} = 240$

Topic Question Set

Q 31 :

The vapour pressure vs. temperature curve for a solution–solvent system is shown below:

[IMAGE 140]

The boiling point of the solvent is ______ °C. [2023]

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Q 33 :

An aqueous solution of volume 300 ${cm}^{3}$ contains 0.63 g of protein. The osmotic pressure of the solution at 300 K is 1.29 mbar. The molar mass of the protein is ________ g ${mol}^{- 1}$ . Given: R = 0.083 L bar $K^{- 1}$ ${mol}^{- 1}$ [2023]

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Q 34 :

Solutions of 12 g of non-electrolyte (A) prepared by dissolving it in 1000 mL of water exerts the same osmotic pressure as that of 0.05 M glucose solution at the same temperature. The empirical formula of A is ${CH}_{2} O$ . The molecular mass of A is ______ g. (Nearest integer) [2023]

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