CBSE Questions for Class 12 Engineering Chemistry Solutions Quiz 10 - MCQExams.com

A $$1.2$$% of solution of $$NaCl$$ is isotonic with $$7.2$$% of solution of glucose. Calculate the van't Hoff's factor of $$NaCl$$ solution.
  • $$2.36$$
  • $$1.50$$
  • $$1.95$$
  • $$1.00$$
Which one of the following electrolytes has the same value of van't Hoff's factor (i) as that of $$Al_2(SO_4)_3$$ (if all are 100% ionised)?
  • $$Al(NO_3)_3$$
  • $$K_4[Fe(CN)_6]$$
  • $$K_2SO_4$$
  • $$K_3[Fe(CN)_6]$$
For an ideal liquid solution, which of the following is unity?
  • Activity coefficient
  • Fugacity coefficient
  • Fugacity
  • Activity
Two liquids $$X$$ and $$Y$$ form an ideal solution at $$300\ K$$, the vapour pressure of the solution containing $$1\ mole$$ of $$X$$ and $$3\ moles$$ of $$Y$$ is $$550$$ mm Hg. At the same temperature, if $$1\ mole$$ of $$Y$$ is further added to this solution, the vapour pressure of the solution increases by $$10\ mm\ Hg$$. Vapour pressure (in mm Hg) of $$X$$ and $$Y$$ in their pure states will be respectively :
  • $$200$$ and $$300$$
  • $$300$$ and $$400$$
  • $$400$$ and $$600$$
  • $$500$$ and $$600$$
Which of the following shows behavior of binary liquid solution?
  • Plot of $${ 1 }/{ { \rho }_{ total } }$$ vs $${ 1 }/{ { Y }_{ A } }$$, mole fraction of $$A$$ in vapour phase
  • Plot of $${ 1 }/{ { \rho }_{ total } }$$ vs $${ 1 }/{ { Y }_{ B } }$$ is linear 
  • Plot of $${ 1 }/{ { \rho }_{ total } }$$ vs $${ 1 }/{( { Y }_{ B } {Y}_{A})}$$ is linear
  • Plot of $${ 1 }/{ { \rho }_{ total } }$$ vs $${ Y }_{ A }$$ is linear
The following is a graph plotted between the vapour pressure of two volatile liquids against their respective mole fractions. 
Which of the following statements is/are correct ?
641905_7ca17c7e4ae14bb5af8eac57e6d62e07.png
  • When $$x_A=1$$ and $$x_B=0$$, then $$p =p^{\circ}_A$$
  • When $$x_B=1$$ and $$x_A=0$$, then $$p =p^{\circ}_B$$
  • When $$x_A=1$$ and $$x_B=0$$, then $$p  =p^{\circ}_B$$
  • When $$x_B=1$$ and $$x_A=0$$, then $$p =p^{\circ}_A$$
Which one of the following is the ratio of the lowering of vapour pressure of 0.1 M aqueous solutions of $$BaCl_2 , NaCl$$ and $$Al_2(SO_4)_3$$ respectively?
  • 3 : 2 : 5
  • 5 : 2 : 3
  • 5 : 3 : 2
  • 2 : 3 : 5
The correct statement among the following is:
  • smoke is carbon dispersed in air
  • butter is water dispersed in fat
  • greater is the valency of ion more will be its coagulating power
  • more is the gold number of a lyophobic sot, more is protecting power
Van't Hoff factor of centimolal solution of $${ K }_{ 3 }\left[ Fe{ \left( CN \right)  }_{ 6 } \right] $$ is $$3.333$$. Calculate the percent dissociation of $${ K }_{ 3 }\left[ Fe{ \left( CN \right)  }_{ 6 } \right] $$.
  • $$33.33$$
  • $$0.78$$
  • $$78$$
  • $$23.33$$

The volume vs. temperature graph of 1 mole of an ideal gas is given below.  

The pressure of the gas (in atm) at $$X,\ Y$$ and $$Z$$, respectively, are:

631238_e9146f532ccf42518d8d1e06c45469a7.png
  • $$0.328, 0.820, 0.820$$
  • $$3.28, 8.20, 3.28$$
  • $$0.238, 0.280, 0.280$$
  • $$32.8, 0.280, 82.0$$
The lowering in vapour pressure is maximum for:
  • 0.1 M urea
  • 0.1 M NaCl
  • 0.1 M MgCl
  • 0.1 M $$K_4[Fe(CN)_6]$$
Relative lowering of vapour pressure is a colligative property because ________.
  • It depends on the concentration of a non-electrolyte solute in solution and does not depend on the nature of the solute molecules.
  • It depends on the number of particles of electrolyte solute in solution and does not depend on the nature of the solute particles
  • It depends on the concentration of a non-electrolyte solute in solution as well as on the nature of the solute molecules.
  • It depends on the concentration of an electrolyte or non-electrolyte solute in solution as well as on the nature of the solute molecules.
In which of the following solvents, KI has highest solubility? 
  • $$C_6H_6(\in = 0)$$
  • $$(CH_3)_2CO(\in = 2)$$
  • $$CH_3OH(\in = 32)$$
  • $$CCl_4(\in = 0)$$
When a liquid that is immiscible with water was steam distilled at $$95.2^o$$C at a total pressure of $$99.652$$ kPa, the distillate contained $$1.27$$ g of the liquid per gram of water. What will be the molar mass of the liquid if the vapour pressure of water is $$85.140$$ kPa at $$95.2^o$$C?
  • $$99.65\ g mol^{-1}$$
  • $$18 \ g mol^{-1}$$
  • $$134.1 \ g mol^{-1}$$
  • $$105.74\ g mol^{-1}$$
Van't Hoff's factor of aq. $${ K }_{ 2 }S{ O }_{ 4 }$$ at infinite dilution has value equal to:
  • $$1$$
  • $$2$$
  • $$3$$
  • Between $$2$$ and $$3$$
If the various terms in the below-given expressions have usual meanings, the van't Hoff factor ($$i$$) cannot be calculated by which of the following expression?
  • $$\pi V=\sqrt { i } nRT$$
  • $$\Delta { T }_{ f }=iK_{ f }.m$$
  • $$\Delta { T }_{ b }=i{ K }_{ b }.m\quad $$
  • $$\cfrac { { P }_{ solvent }^{ o }-{ P }_{ solution } }{ { P }_{ solvent }^{ o } } =i\left( \cfrac { n }{ N+n } \right) $$
$$12$$g of a non-volatile solute dissolved in $$108$$g of water produces the relative lowering of the vapour pressure of $$0.1$$. The molecular mass of the solute is:
  • $$80$$
  • $$60$$
  • $$20$$
  • $$40$$
Two liquids $$X$$ and $$Y$$ from an ideal solution. At $$300K$$, a vapour pressure of the solution containing $$1$$ mol of $$X$$ and $$3$$ mol of $$Y$$ is $$550$$ $$mm \ Hg$$. At the same temperature, if $$1$$ mol of $$Y$$ is further added to this solution, a vapour pressure of the solution increased by $$10$$ $$mm \ Hg$$. Vapour pressure ( in mmHg) of $$X$$ and $$Y$$ in their pure states will be respectively: 
  • $$300$$ and $$400$$
  • $$400$$ and $$600$$
  • $$500$$ and $$600$$
  • $$200$$ and $$300$$
1 mole of liquid A and 9 moles of liquid B are mixed to form a solution. If $$P_B^o=400mm$$ of Hg and $$P_B^o=200mm$$ of Hg at a temperature 'T' and normal boiling point of liquid B is 300 K then answer the questions that follow. 
Given data: $$K_b=2.7\ K\ kg\ mol^{-1},$$ Molar mass of $$B=100$$
If 'A' is perfectly non-volatile and it dimerises to an extent of 60% then what will be the vapour pressure of the solution.
  • $$360 mm$$ of Hg
  • $$\displaystyle \frac{3600}{9.7} mm$$ of Hg
  • $$\displaystyle \frac{4000}{9.7} mm$$ of Hg
  • $$36 mm$$ of Hg
The values of van't Hoff factors for $$KCl, NaCl$$ and $$K_2SO_4$$ respectively are: 
  • $$1, 1, 2$$
  • $$1, 1, 1$$
  • $$2, 2, 3$$
  • $$2, 3, 2$$
$$CuSO_4$$$$\cdot$$$$5H_2O(s)$$$$\rightleftharpoons$$ $$CuSO_4\cdot$$ 3$$H_2O(s)$$ + $$2H_2O(g)$$; $$K_p$$ = 4$$\times10^{-4}$$ $$atm^2$$ if the vapour pressure of water is 38 torr then percentage of relative humidity is: ( Assume all data at constant temperature)
  • $$4$$
  • $$10$$
  • $$40$$
  • $$none\ of\ these$$
Two closed vessels of an equal volume containing air at pressure $$P_1$$ and temperature $$T_1$$ are connected to each other through a narrow tube. If the temperature in one of the vessels is now maintained at $$T_1$$ and that in the other at $$T_2$$, what will be the pressure in the vessels?
  • $$\dfrac{2P_1T_1}{T_1+T_2}$$
  • $$\dfrac{T_1}{2P_1T_2}$$
  • $$\dfrac{2P_1T_2}{T_1+T_2}$$
  • $$\dfrac{2P_1}{T_1+T_2}$$
The vapour pressure of pure benzene at a certain temperature is $$640\ mm\ Hg$$. A non-volatile solute weighing $$2.175\ g$$ is added to $$39.0\ g$$ of benzene. The vapour pressure of solution is $$600\ mm\ Hg$$. What is the molar mass of the solute?
  • $$72.1\ g\ mol^{-1}$$.
  • $$70.6\ g\ mol^{-1}$$.
  • $$69.4\ g\ mol^{-1}$$.
  • $$56.2\ g\ mol^{-1}$$.
Equal mass of $$H_2$$, $$He$$ and $$CH_4$$ are mixed in empty container at $$300$$K, when total pressure is $$2.6$$ atm. The partial pressure of $$H_2$$ in the mixture is:
  • $$2.1$$ atm.
  • $$1.6$$ atm.
  • $$0.8$$ atm.
  • $$0.2$$ atm.
$$18$$ g glucose ($$C_6H_{12}O_6$$) is added to $$178.2$$ g of water. The vapour pressure of this aqueous solution at $$100^0C$$ in torr is:
  • $$7.60$$
  • $$76.00$$
  • $$752.40$$
  • $$759.00$$
$$CaCl_2.6H_2O(s) \rightleftharpoons CaCl_2(s) +6H_2O(g);$$ $$K_p=6.4\times 10^{-17}$$. Excess solid $$CaCl_2.6H_2O$$ and $$CaCl_2$$ are taken in a container containing some water vapours at a pressure of 1.14 torr at a particular temperature. Which of the following is true?
  • $$CaCl_2(s)$$ acts as drying agent under given condition.
  • $$CaCl_2(s)$$ acts as hygroscopic substance given condition.
  • $$CaCl_2.6H_2O(s)$$ acts as effluoroscent substance
  • Mass of $$CaCl_2.6H_2O(s)$$ increases due to some reaction.
A gaseous mixture contains $$56\ g\ N_{2}. 44\ g\ CO_{2}$$ and $$16\ g\ CH_{4}$$. The total pressure of the mixture is $$720\ mm\ Hg$$. The partial pressure of $$CH_4$$ in mm Hg is:
  • $$620\ mm$$ of $$Hg$$
  • $$180\ mm$$ of $$Hg$$
  • $$160\ mm$$ of $$Hg$$
  • $$200\ mm$$ of $$Hg$$
If $${ PCl }_{ 5 }$$ is 80% dissociated at $$250$$ then its vapour density at room temperature will be:
  • 56.5
  • 104.25
  • 101.2
  • 52.7
Two containers, X and Y at 300K and 350K with water vapour pressures 22 mm and 40 mm respectively a are connected, initially closed with a valve. If the valves opened.
  • The final pressure in each container is 31 mm
  • The final pressure in each container is 40 mm
  • Mass of $$H_{2}O$$(l) in X increases
  • Mass of $$H_{2}O$$(l) in Y decreases roar.
A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour  pressure of 2.8 kPa at 298 K. Further 18 g  of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 k Calculate vapour pressure of water at 298K?
  • $$4.53kPa$$
  • $$3.53kPa$$
  • $$5.53kPa$$
  • $$6.53kPa$$
The vapour pressure of $$C_6H_6$$ and $$C_7H_8$$ mixture at $$50^{\circ}C$$ is given by $$p=179X_B+92$$ where $$X_B$$ is the mole fraction of $$C_6H_6$$.
Calculate (in mm) Vapour pressure of liquid mixture obtained by mixing $$936 \, g\ C_6H_6 \, $$ and $$736\ g$$ toluene is:
  • 300 mm Hg
  • 250 mm Hg
  • 199.4 mm Hg
  • 180.6 mm Hg
The vapour pressure of two pure liquids A and B which form an ideal solution are 1000 and 1600 torr respectively at 400 K. A liquid solution of A and B for which the mole fraction of A is 0.60 is contained in a cylinder by a piston on which the pressure can be varied. The solution use slowly vapourised at 400 K by decreasing the applied pressure. What is the composition of last droplet of liquid remaining in equilibrium with vapour?
  • $$X_A= 0.30, X_B= 0.70$$
  • $$X_A= 0.40, X_B= 0.60$$
  • $$X_A= 0.70, X_B= 0.30$$
  • $$X_A= 0.50, X_B= 0.50$$
Pressure of the gas in column (1) is :
876957_072edef6ea864bf2a035fdce2f1d33b7.JPG
  • 60 cm of Hg
  • 55 cm of Hg
  • 50 cm of Hg
  • 45 cm of Hg
$$P_A \, = \, X_AP_A$$ and $$P_B \, = \, X_BP_B$$
$$P_T \, = \, X_AP_A \, + \, X_BP_B$$
Vapour pressure of mixtures of Benzene $$(C_6H_6)$$ and toluene $$(C_7H_8)$$ at $$50^{\circ}C$$ are given by $$P_M \, = \, 179X_B \, + \, 92$$ where $$X_B$$ is mole fraction of $$C_6H_6$$.
What is the vapour pressure of pure liquids?
  • $$P_B \, = \, 92 mm, \, P_T \, = \, 179 mm$$
  • $$P_B \, = \, 271 mm, \, P_T \, = \, 92 mm$$
  • $$P_B \, = \, 180 mm, \, P_T \, = \, 91 mm$$
  • None of these
The vapour density of undecomposed $${ N }_{ 2 }{ O }_{ 4 }$$ isWhen heated, vapour density decreases to $$24.5$$ due to its dissociation to $${ N O}_{ 2 }$$. The percentage dissociation of $${ N }_{ 2 }{ O }_{ 4 }$$ at the final temperature is:
  • $$88$$
  • $$60$$
  • $$40$$
  • $$70$$
Vapour pressure of $$CC{l}_{4}$$ at $$25^{O}C$$ is 143mm Hg. 0.5gm of a non-volatile solute (mol. wt. 65) is dissolved in 100ml of $$CC{l}_{4}$$. Find the vapour pressure of the solution.
(Density of $$CC{l}_{4} = 1.58 gm/{cm}^{3}$$)
  • 141.93 mm
  • 94.39 mm
  • 199.34 mm
  • 143.99 mm
Formation of a solution form two component can be considered as:
(1) Pure solvent $$\rightarrow$$separated solvent molecules, $${ \Delta H }_{ 1 }$$
(2) Pure solute $$\rightarrow$$separated solute molecules, $${ \Delta H }_{ 2 }$$
(3) Separated solvent and solute molecules $$ \rightarrow$$ solution, $$ { \Delta H }_{ 3 }$$
The solution so formed will be ideal if:
  • $$ { \Delta H }_{ soln }\ =\ { \Delta H }_{ 1 }-{ \Delta H }_{ 2 }-{ \Delta H }_{ 3 }$$
  • $$ { \Delta H }_{ soln }\ =\ { \Delta H }_{ 3 }-{ \Delta H }_{ 1 }-{ \Delta H }_{ 2 }$$
  • $${ \Delta H }_{ soln }\ =\ { \Delta H }_{ 1 }+{ \Delta H }_{ 2 }+{ \Delta H }_{ 3 }$$
  • $${ \Delta H }_{ soln }\ =\ { \Delta H }_{ 1 }{ +\Delta H }_{ 2 }-{ \Delta H }_{ 3 }$$
The vapour pressure of two pure liquids $$A$$ and $$B$$, that form an ideal solution are $$100$$ and $$900$$ torr respectively at temperature $$T$$. This liquid solution of $$A$$ and $$B$$ is composed of $$1\ mole$$ of $$A$$ and $$1\ mole$$ of $$B$$. What will be the pressure, when $$1$$ mole of mixture has been vapourized?
  • $$800\ torr$$
  • $$500\ torr$$
  • $$300\ torr$$
  • None of these
Solubility of $$CO_{2}(g)$$ in water at $$1\ bar$$ and $$25^{\circ}C$$ involves the following equilibria:
$$CO_{2}(g) \rightleftharpoons CO_{2}(aq); K_{1}^{\circ} = 0.04$$
$$CO_{2}(aq.) + H_{2}O(l) \rightleftharpoons H^{+}(aq.) + HCO_{3}^{-}(aq); K_{2}^{\circ} = 4\times 10^{-6}$$
$$HCO_{3}^{-}(aq.) \rightleftharpoons H^{+}(aq.) + CO_{3}^{2-}(aq); K_{3}^{\circ} = 5\times 10^{-11}$$
$$[H^{+}]$$ in saturated solution of $$CO_{2}(g)$$ water is ?
  • $$0.04\ M$$
  • $$4\times 10^{-3}M$$
  • $$4\times 10^{-4}M$$
  • $$2\times 10^{-3}M$$
The vapour pressure of two pure liquids A and B, that form an ideal solution are $$100$$ and $$900$$ torr respectively at temperature T. This liquid solution of A and B is composed of $$1$$ mole of A and $$1$$ mole of B. What will be the pressure, when $$1$$ mole of mixture has been vapourized?
  • $$800$$torr
  • $$500$$torr
  • $$300$$torr
  • None of these
Two moles of pure liquid 'A' $$(P_{A}^{0} =80mm$$ of Hg) and $$3$$ moles of pure liquid 'B' ($$P_{B}^{0} = 120mm$$ of Hg) are mixed. Assuming ideal behaviour?
  • Vapour pressure of the mixture is $$104$$mm of Hg
  • Mole fraction of liquid 'A' in Vapour pressure is $$0.3077$$
  • Mole fraction of 'B' in Vapour pressure is $$0.692$$
  • Mole fraction of 'B' in Vapour pressure is $$0.785$$
Vapour pressure of $$CCl_4$$ at $$25^0$$C is $$143$$mm Hg. $$0.5$$ gm of a non-volatile solute (mol.wt.$$65$$) is dissolved in $$100$$ ml of $$CCl_4$$. Find the vapour pressure of the solution. (Density of CCl_4 = $$1.58 gm/cm^3$$)
  • $$141.93$$mm
  • $$94.39$$mm
  • $$199.34$$mm
  • $$143.99$$mm
Directions: In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice:

Assertion 
Amalgam of mercury with sodium is an Assertion as: Amalgam of solid solutions. 
Reason 
Mercury is solvent and sodium is solute in the solution.
  • If both assertion and reason are true and reason is the correct explanation of assertion.
  • If both assertion and reason are true but reason is not the correct explanation of assertion.
  • If assertion is true but reason is false.
  • If both assertion and reason are false.
Two liquids $$X$$ and $$Y$$ are perfectly immiscible. If $$X$$ and $$Y$$ have molecular masses in ration $$1 : 2$$, the total vapour pressure of a mixture of $$X$$ and $$Y$$ prepared in weight ratio $$2 : 3$$ should be:$$(P_{X}^{0} = 400\ torr, P_{Y}^{0} = 200\ torr)$$.
  • $$314\ torr$$
  • $$466.7\ torr$$
  • $$600\ torr$$
  • $$700\ torr$$
The vapour pressure of three liquids $$P, Q$$ and $$R$$, of nearly equal molecular masses is shown as a function of temperature. 
The correct statement is:

889743_b3ff027164634f12ba30a9e4a205f98a.png
  • The normal boiling points follow the order $$P > Q > R$$
  • The variation of pressure with respect to temperature for each liquid is given by $$\displaystyle\frac{dP}{dT}=\frac{K}{T^2}$$, where K is a constant
  • The strength of intermolecular interactions follows the order $$P > Q > R$$
  • The normal boiling point of $$Q$$ is close to $$65^o$$C
$$X,Y$$ and $$Z$$ in the given graph are?
932582_ab446ecc9fe946d2b73c4b1c74d32a2a.JPG
  • $$X={p}_{1}+{p}_{2},Y=1,Z=0$$
  • $$X={p}_{1}+{p}_{2},Y=0,Z=0$$
  • $$X={p}_{1}\times {p}_{2},Y=0,Z=0$$
  • $$X={p}_{1}-{p}_{2},Y=1,Z=0$$
A chemist has $$m$$ gm of salt water that is $$m$$% salty. How many gram of salt must he add to make a solution that is $$2m$$% salty?
  • $$\dfrac {m}{100 + m}$$
  • $$\dfrac {2m}{100 - 2m}$$
  • $$\dfrac {m^{2}}{100 - 2m}$$
  • $$\dfrac {m^{2}}{100 + 2m}$$
Two liquids X and Y are perfectly immiscible. If X and Y have molecular masses in ratio 1 : 2, the total vapour pressure of a mixture of X and Y prepared in weight ratio 2 : 3 should be ($$Px^0 = 400 torr, Py^0 = 200 torr$$)
  • 314 torr
  • 466.7 torr
  • 600 torr
  • 700 torr
CuSO$$_4.$$5$$H_2O$$(s) $$\rightleftharpoons$$ CuSO$$_4$$.3H$$_2O$$(s) + 2H$$_2O$$(g); $$k_p$$ = 4 $$10^{4}$$ atm$$^2.$$ If the vapour pressure of water is 38 torr then percentage of relative humidity is : (Assume all data at constant temperature)
  • 4
  • 10
  • 40
  • None of these
The relative lowering in vapour pressure is proportional to the ratio of number of :
  • solute molecules to solvent molecules
  • solvent molecules to solute molecules
  • solute molecules to the total number of molecules to the total number of molecules in solution
  • solvent molecules to the total number of molecules in solution
0:0:1


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