Problem 64
A quantity of \(3.125 \mathrm{~g}\) of a mixture of \(\mathrm{KCl}\) and \(\mathrm{NaCl}\) dissolved in \(1 \mathrm{~kg}\) of water produces a depression of \(0.186^{\circ} \mathrm{C}\) in freezing point. The molar ratio of \(\mathrm{KCl}\) to \(\mathrm{NaCl}\) in the solution (assuming complete dissociation of the salts) is \(\left(K_{f}=1.86\right.\) deg \(/\) molal \()\) (a) \(1: 3\) (b) \(2: 3\) (c) \(1: 1\) (d) \(3: 1\)
Problem 64
The molal boiling point elevation constant of water is \(0.513^{\circ} \mathrm{C} \mathrm{kg} \mathrm{mol}^{-1}\). When \(0.1\) mole of sugar is dissolved \(200 \mathrm{~g}\) of water, the solution boils under a pressure of 1 atm at (a) \(100.513^{\circ} \mathrm{C}\) (b) \(102.565^{\circ} \mathrm{C}\) (c) \(100.256^{\circ} \mathrm{C}\) (d) \(101.025^{\circ} \mathrm{C}\)
Problem 66
An aqueous solution of \(10 \%\) NaCl (consider ideal behaviour of the solution) is cooled. It will allow some (a) \(\mathrm{NaCl}\) to crystallize (b) water to freeze (c) water to solidify along with some \(\mathrm{NaCl}\) (d) precipitation of \(\mathrm{NaCl}\)
Problem 67
If 1 mole of a non-volatile, non-electrolyte solute in \(1000 \mathrm{~g}\) of water depresses the freezing point by \(1.86^{\circ} \mathrm{C}\), what will be the freezing point of a solution of 1 mole of the solute in \(500 \mathrm{~g}\) of water? (a) \(-0.93^{\circ} \mathrm{C}\) (b) \(-1.86^{\circ} \mathrm{C}\) (c) \(3.72^{\circ} \mathrm{C}\) (d) \(-3.72^{\circ} \mathrm{C}\)
Problem 68
What is the molecular mass of a nonionizing solid if \(10 \mathrm{~g}\) of this solid, when dissolved in \(100 \mathrm{~g}\) of water, forms a solution, which freezes at \(-1.24^{\circ} \mathrm{C}\) ? \(K_{\mathrm{f}}\left(\mathrm{H}_{2} \mathrm{O}\right)=1.86^{\circ} \mathrm{C} \mathrm{kg} \mathrm{mol}^{-1}\) (a) 250 (b) 150 (c) 120 (d) 75
Problem 70
When the depression in freezing point is carried out, the equilibrium exist between (a) liquid solvent and solid solvent (b) liquid solute and solid solvent (c) liquid solute and solid solute (d) liquid solvent and solid solute
Problem 72
Among the colligative properties of solution, which one is the best method for the determination of molecular masses of proteins and polymers? (a) osmotic pressure (b) lowering in vapour pressure (c) lowering in freezing point (d) elevation in boiling point
Problem 77
Van't Hoff's factor for a dilute solution of \(\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) is (a) \(4.0\) (b) \(0.25\) (c) \(5.0\) (d) \(3.0\)
Problem 79
The limiting value of Van't Hoff's factor for \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) is (a) 2 (b) 3 (c) 4 (d) 5
Problem 82
For each of the following dilute solutions, Van't Hoff's factor is equal of 3 , except (a) \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (b) \(\mathrm{CaF}_{2}\) (c) \(\mathrm{K}_{3} \mathrm{PO}_{4}\) (d) \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\)
