20 questions from 2026
Which one of the following graphs accurately represents the plot of partial pressure of $\text{CS}_2$ vs its mole fraction in a mixture of acetone and $\text{CS}_2$ at constant temperature?
At \( T(\mathrm{K}) \), \( 2 \) moles of liquid \( \mathrm{A} \) and \( 3 \) moles of liquid \( \mathrm{B} \) are mixed. The vapour pressure of ideal solution formed is \( 320 \, \text{mm Hg} \). At this stage, one mole of \( \mathrm{A} \) and one mole of \( \mathrm{B} \) are added to the solution. The vapour pressure is now measured as \( 328.6 \, \text{mm Hg} \). The vapour pressure (in mm Hg) of \( \mathrm{A} \) and \( \mathrm{B} \) are respectively:
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 solution is ideally dilute.
Statement II: \( K_H \) does not differ for the same solute in different solvents.
In the light of the above statements, choose the correct answer from the options given below:
‘\( W \) g’ of a non-volatile electrolyte solid solute of molar mass ‘\( M \)’ \( \mathrm{g \, mol^{-1}} \) when dissolved in \( 100 \, \mathrm{mL} \) water, decreases vapour pressure of water from \( 640 \, \mathrm{mm \, Hg} \) to \( 600 \, \mathrm{mm \, Hg} \). If aqueous solution of the electrolyte boils at \( 375 \, \mathrm{K} \) and \( K_b \) for water is \( 0.52 \, \mathrm{K \, kg \, mol^{-1}} \), then the mole fraction of the electrolyte solute (\( x_2 \)) in the solution can be expressed as (Given: density of water = \( 1 \, \mathrm{g/mL} \) and boiling point of water = \( 373 \, \mathrm{K} \))
Two liquids \( A \) and \( B \) form an ideal solution. At \( 320 \, \text{K} \), the vapour pressure of the solution, containing \( 3 \) mol of \( A \) and \( 1 \) mol of \( B \) is \( 500 \, \text{mm Hg} \). At the same temperature, if \( 1 \) mol of \( A \) is further added to this solution, vapour pressure of the solution increases by \( 20 \, \text{mm Hg} \). Vapour pressure \( \)(in mm Hg\( \)) of \( B \) in pure state is _________ \( \). \( \)(Nearest integer\( \))
Elements P and Q form two types of non-volatile, non-ionizable compounds \( \mathrm{PQ} \) and \( \mathrm{PQ_2} \). When \( 1 \, \mathrm{g} \) of \( \mathrm{PQ} \) is dissolved in \( 50 \, \mathrm{g} \) of solvent ‘A’, \( \Delta T_b \) was \( 1.176 \, \mathrm{K} \) while when \( 1 \, \mathrm{g} \) of \( \mathrm{PQ_2} \) is dissolved in \( 50 \, \mathrm{g} \) of solvent ‘A’, \( \Delta T_b \) was \( 0.689 \, \mathrm{K} \). \( (K_b \) of ‘A’ \( = 5 \, \mathrm{K\,kg\,mol^{-1}} ) \). The molar masses of elements P and Q (in \( \mathrm{g\,mol^{-1}} \)) respectively, are:
Given below are two statements:
Statement (I): \( 1,2,3 \)-Trihydroxypropane can be separated from water by simple distillation.
Statement (II): An azeotropic mixture cannot be separated by fractional distillation.
In the light of the above statements, choose the correct answer from the options given below:
Solution A is prepared by dissolving \( 1 \, \mathrm{g} \) of a protein (molar mass \( = 50000 \, \mathrm{g \, mol^{-1}} \)) in \( 0.5 \, \mathrm{L} \) of water at \( 300 \, \mathrm{K} \). Its osmotic pressure is \( x \) bar. Solution B is made by dissolving \( 2 \, \mathrm{g} \) of same protein in \( 1 \, \mathrm{L} \) of water at \( 300 \, \mathrm{K} \). Osmotic pressure of solution B is \( y \) bar. Entire solution of A is mixed with entire solution of B at same temperature. The osmotic pressure of resultant solution is \( z \) bar. \( x \), \( y \) and \( z \) respectively are: \( (R = 0.083 \, \mathrm{L \, bar \, mol^{-1} \, K^{-1}}) \)
At \( 298 \, \text{K} \), the mole percentage of \( \mathrm{N_2(g)} \) in air is \( 80\% \). Water is in equilibrium with air at a pressure of \( 10 \, \text{atm} \). What is the mole fraction of \( \mathrm{N_2(g)} \) in water at \( 298 \, \text{K} \)? ( \( K_H \) for \( \mathrm{N_2} \) is \( 6.5 \times 10^{7} \, \text{mm Hg} \) )
Consider a solution of \( \mathrm{CO_2(g)} \) dissolved in water in a closed container. Which one of the following plots correctly represents variation of \( \log \) (partial pressure of \( \mathrm{CO_2} \) in vapour phase above water) [y-axis] with \( \log \) (mole fraction of \( \mathrm{CO_2} \) in water) [x-axis] at \( 25^\circ \mathrm{C} \)?
A solution is prepared by dissolving \( 0.3 \, \text{g} \) of a non-volatile non-electrolyte solute 'A' of molar mass \( 60 \, \text{g mol}^{-1} \) and \( 0.9 \, \text{g} \) of a non-volatile non-electrolyte solute 'B' of molar mass \( 180 \, \text{g mol}^{-1} \) in \( 100 \, \text{mL} \) \( \mathrm{H_2O} \) at \( 27^{\circ}\mathrm{C} \). Osmotic pressure of the solution will be \( [\text{Given: } R = 0.082 \, \mathrm{L\, atm\, K^{-1}\, mol^{-1}}] \)
Which of the following statements are not correct?
A. For water, magnitude of \( K_b \) is more than the magnitude of \( K_f \).
B. The elevation in boiling point of water when a non-volatile solute is added to it is larger in magnitude than its depression in freezing point.
C. Osmotic pressure measurement is preferred over any other colligative property to determine molar mass of proteins and polymers.
D. The dimerised form of benzoic acid in benzene is 
Choose the correct answer from the options given below:
Given below are two statements:
Given: Molar mass of \( \mathrm{C, H, O, Cl} \) are \( 12 \), \( 1 \), \( 16 \) and \( 35.5 \, \mathrm{g\, mol^{-1}} \), respectively:
Statement-I: In \( 30\% \) (w/w) solution of methanol in \( \mathrm{CCl_{4}} \) (at \( T \, \mathrm{K} \)), the mole fraction of \( \mathrm{CCl_{4}} \) is equal to \( 0.33 \).
Statement-II: Mixture of methanol and \( \mathrm{CCl_{4}} \) shows positive deviation from Raoul’s law.
In the light of the above statements, choose the correct answer from the options given below:
The osmotic pressure of a living cell is \( 12 \, \text{atm} \) at \( 300 \, \text{K} \). The strength of sodium chloride solution that is isotonic with the living cell at this temperature is _____ \( \text{g L}^{-1} \). (Nearest integer)
Given: \( R = 0.08 \, \text{L atm K}^{-1} \, \text{mol}^{-1} \)
Assume complete dissociation of NaCl
(Given: Molar mass of Na and Cl are \( 23 \) and \( 35.5 \, \text{g mol}^{-1} \) respectively.)
At \( 27^\circ \text{C} \), \( 0.1 \, \text{M} \), \( 1 \, \text{L} \) \( \mathrm{K_4[Fe(CN)_6]} \) aqueous solution and \( 0.1 \, \text{M} \), \( 1 \, \text{L} \) \( \mathrm{FeCl_3} \) aqueous solution are placed in a container separated by a semi permeable membrane AB. Assume complete dissociation of both the solutes. Which of the following statement is correct? 
\( 19.5 \, \text{g} \) of fluoro acetic acid (molar mass \( = 78 \, \text{g mol}^{-1} \)) is dissolved in \( 500 \, \text{g} \) of water at \( 298 \, \text{K} \). The depression in the freezing point of water was \( 1^\circ \text{C} \). What is \( K_a \) of fluoro acetic acid ? (For water, \( K_f = 1.86 \, \text{K kg mol}^{-1} \)). Assume molarity and molality to have same values.
Two liquids \( \mathrm{A} \) and \( \mathrm{B} \) form an ideal solution at temperature \( T \, \text{K} \). At \( T \, \text{K} \), the vapour pressures of pure \( \mathrm{A} \) and \( \mathrm{B} \) are \( 55 \) and \( 15 \, \text{kN m}^{-2} \) respectively. What is the mole fraction of \( \mathrm{A} \) in solution of \( \mathrm{A} \) and \( \mathrm{B} \) in equilibrium with a vapour in which the mole fraction of \( \mathrm{A} \) is \( 0.8 \)?
A substance 'X' (\( 1.5 \, \text{g} \)) dissolved in \( 150 \, \text{g} \) of a solvent 'Y' (molar mass \( = 300 \, \text{g mol}^{-1} \)) led to an elevation of the boiling point by \( 0.5 \, \text{K} \). The relative lowering in the vapor pressure of the solvent 'Y' is _____ \( \times 10^{-2} \). (nearest integer)
[Given: \( K_b \) of the solvent \( = 5.0 \, \text{K kg mol}^{-1} \) ]
Assume the solution to be dilute and no association or dissociation of X takes place in solution.
A non-volatile, non-electrolyte solid solute when dissolved in \( 40 \, \text{g} \) of a solvent, the vapour pressure of the solvent decreased from \( 760 \, \text{mm Hg} \) to \( 750 \, \text{mm Hg} \). If the same solution boils at \( 320 \, \text{K} \), then the number of moles of the solvent present in the solution is ________. (Nearest integer)
[Given: boiling point of the pure solvent \( = 319.5 \, \text{K} \). \( K_b \) of the solvent \( = 0.3 \, \text{K kg mol}^{-1} \)]
\( 20 \, \text{g} \) hemoglobin in a \( 1 \, \text{L} \) aqueous solution (A) at \( 300 \, \text{K} \) is separated from pure water by semi permeable membrane. At equilibrium the height of solution in a tube dipped in a solution (A) is found to be \( 80.0 \, \text{mm} \) higher than the tube dipped in water.
\(
\text{The molar mass of hemoglobin is }
\underline{\hspace{3cm}}
\ \mathrm{kg\,mol^{-1}}.
\qquad
\text{(Nearest integer)}
\)
\(
(\text{Given: }
g=10\,\mathrm{m\,s^{-2}},\quad
R=8.3\,\mathrm{kPa\,dm^3\,K^{-1}\,mol^{-1}},\quad
\text{density of solution}=1000\,\mathrm{kg\,m^{-3}}
)\)
