List of top Chemistry Questions on Colligative Properties asked in CBSE CLASS XII

Calculate the freezing point of a solution when 10.5 g of MgBr$_2$ was dissolved in 250 g of water, assuming MgBr$_2$ undergoes complete dissociation. Given: \[ \text{Molar mass of MgBr}_2 = 184 \, g\,mol^{-1} \] \[ K_f \text{ for water} = 1.86 \, K\,kg\,mol^{-1} \] (ii) Write two differences between ideal and non-ideal solutions.
1.00 molal aqueous solution of trichloroacetic acid is heated to its boiling point. Boiling point of this solution was found to be \(100.18^\circ C\). Calculate the van't Hoff factor for trichloroacetic acid. (Given : \(K_b\) for water \(= 0.512\;K\,kg\,mol^{-1}\))
Explain why, on addition of 1 mol of KCl to 1 litre of water, the boiling point of water increases, while the addition of 1 mol of methyl alcohol to 1 litre of water decreases the boiling point.
Which of the following solutions will have the highest osmotic pressure ?
Which of the following solutions will have the lowest freezing point in water?
Explain why, on addition of 1 mol of KCl to 1 litre of water, the boiling point of water increases, while the addition of 1 mol of methyl alcohol to 1 litre of water decreases the boiling point.
State Raoult’s law for a solution containing volatile components. Why is the vapour pressure of an aqueous solution of glucose lower than that of water?
The freezing point of one molal KCl solution, assuming KCl to be completely dissociated in water, is: (\(K_f\) for water = 1.86 K kg mol\(^{-1}\))
A solution of acetone in ethanol:
Vapour pressure of pure water at 298 K is 24.8 mm Hg. Calculate the lowering in vapour pressure of an aqueous solution which freezes at –0.3°C. (K\(_f\) of water = 1.86 K kg mol\(^{-1}\))

A solution of glucose (molar mass = 180 g mol\(^{-1}\)) in water has a boiling point of 100.20°C. Calculate the freezing point of the same solution. Molal constants for water \(K_f\) and \(K_b\) are 1.86 K kg mol\(^{-1}\) and 0.512 K kg mol\(^{-1}\) respectively. 

Give reasons: 
(a) Cooking is faster in a pressure cooker than in an open pan. 
(b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution? 
© What change in temperature would you observe after mixing liquids X and Y? 

In case of association, abnormal molar mass of solute will: 

A solution containing 2 g of glucose (M = 180 g mol$^{-1}$) in 100 g of water is prepared at 303 K. If the vapour pressure of pure water at 303 K is 32.8 mm Hg, what would be the vapour pressure of the solution?
Calculate the mass of CaCl$_2$ (molar mass = 111 g mol$^{-1}$) to be dissolved in 500 g of water to lower its freezing point by 2K, assuming that CaCl$_2$ undergoes complete dissociation.
Complete the following ionic equation:
Cr2O72− + 14H+ + 6e− →
Define colligative property. Which colligative property is preferred for the molar mass determination of macromolecules?
Assertion (A): When NaCl is added to water, a depression in freezing point is observed.
Reason (R): NaCl undergoes dissociation in water.
For an electrolyte undergoing association in a solvent, the van’t Hoff factor: