Classes
Class 9Class 10First YearSecond Year
$\mathrm{Q} 21.4 .675 \mathrm{~g} of a compound with empirical formula \mathrm{C}_{3} \mathrm{H}_{3} \mathrm{O} were dissolved in 212.5 \mathrm{~g} of pure benzene. The freezing point of solution was found 1.02^{\circ} \mathrm{C} less than that of pure benzene. The molal freezing point constant of benzene is 5.1^{\circ} \mathrm{C} . Calculate (i) the relative molar mass and (ii) the molecular formula of the compound.$

$Q13. What is Raoults law. Give its three statements. How this law can help us to understand the ideality of a solution.$

$1. A solution contains 50 \mathrm{~g} of sugar dissolved in 450 \mathrm{~g} of water. What is concentration of this solution?$

$Worked Example 2: The pH of a solution is 9.63. Compute its hydrogen ion concentration.$

$(c) Calculate the concentration of a solution in terms of molality which is obtained by mixing 250 \mathrm{~g} of 20 \% solution of \mathrm{NaCl} with 200 \mathrm{~g} of 40 \% solution of \mathrm{NaCl} .$

$Q 23. 3 g of a non-volatile non-electrolyte solute X are dissolved in 50 \mathrm{~g} of ether (molar mass = 74) at 293 \mathrm{~K} . The vapour pressure of ether falls from 442 torr to 426 torr under these conditions. Calculate the molar mass of solute X .(Ans: 122.6 \mathrm{~g} \mathrm{~mol}^{-1} )$

$9. Tyndall effect is shown by:(a) sugar solution(b) paints(c) jelly(d) chalk solution$