184.
$$4\,L$$ of $$0.02\,M$$ aqueous solution of $$NaCl$$ was diluted by adding one litre of water. The molality of the resultant solution is _____________.
$$\eqalign{
& {M_1}{V_1} = {M_2}{V_2};0.02\,M \times 4\,L = {M_2} \times 5\,L \cr
& {M_2} = \frac{{0.02 \times 4}}{5} = 0.016\,M \cr} $$
Here, molality will be equal to molarity as for $$NaCl,$$ molecular weight is equal to its equivalent weight.
185.
What amount of $$CaC{l_2}\left( {i = 2.47} \right)$$ is dissolved in 2 litres of water so that its osmotic pressure is $$0.5\,atm$$ at $${27^ \circ }C?$$
$$\eqalign{
& {\text{Number of moles of urea}} = \frac{{120}}{{60}} = 2 \cr
& {\text{Total mass of solution = 1000 + 120 = 1120}}g \cr
& {\text{Total volume of solution (in L) = }}\frac{{Mass}}{{Density}} \cr
& = \frac{{1120}}{{1.15 \times {{10}^3}}} = \frac{{112}}{{115}}L \cr
& {\text{Molarity of the solution}} = \frac{{{\text{Number}}\,{\text{of}}\,{\text{moles}}}}{{{\text{Volume}}\,{\text{in}}\,{\text{L}}}} \cr
& = \frac{{2 \times 115}}{{112}} = 2.05\,mol\,{L^{ - 1}} \cr} $$
188.
The value of Henry's law constant for some gases at $$293\,K$$ is given below. Arrange the gases in the increasing order of their solubility.
$$\eqalign{
& He:144.97\,kbar,{H_2}:69.16\,kbar, \cr
& {N_2}:76.48\,kbar,{O_2}:34.86\,kbar \cr} $$
$$PQ$$ corresponds to increase in vapour pressure of solvent with temperature and $$XY$$ corresponds to increase in vapour pressure of solution with temperature. $$\Delta T$$ is the elevation in boiling point of a solution.
190.
Choose the correct statement with respect to the vapour pressure of a liquid among the following :
A
Increases linearly with increasing temperature
B
Increases non-linearly with increasing temperature
C
Decreases linearly with increasing temperature
D
Decreases non-linearly with increasing temperature
Answer :
Increases non-linearly with increasing temperature