CBSE Questions for Class 12 Engineering Chemistry Solutions Quiz 3 - MCQExams.com

The vapour pressure of a deliquescent substance is:
  • equal to the atmospheric pressure
  • equal to that of the water vapour in air
  • greater than that of the water vapour in air
  • less than that of the water vapour in air
Which of the following plots represents an ideal binary mixture?
  • Plot of $$P_{total} \  v/s \ 1/X$$ is linear ( $$X_{B}$$= mole fraction of 'B' in liquid phase).
  • Plot of $$P_{total} \ v/s \ Y_{A}$$ is linear $$(Y_{B}=$$ mole fraction of 'A' in vapour phase)
  • Plot of $$\dfrac{1}{P_{total}} \ v/s \ Y_{A}$$ is linear
  • Plot of $$\dfrac{1}{P_{total}} \ v/s \ Y_{B}$$ is non linear
The vapour pressure of a solution in a dilute solution is influenced by :
  • temperature of solution
  • mole fraction of solute
  • melting point of solute
  • degree of dissociation of solute
Which of the following represents correctly the changes in thermodynamic properties during the formation of 1 mol of an ideal binary solution.
Ideal solution is formed when its components :
  • have zero heat of mixing
  • have zero volume change
  • obey Raoult's law
  • can be converted into gases
The Van't Hoff factor for a dilute aqueous solution of glucose is :
  • $$Zero$$
  • $$1.0$$
  • $$1.5$$
  • $$2.0$$
The incorrect statement is:
  • Vapour pressure of a liquid always increases by increasing temperature.
  • Vapour pressure only depends on temperature and not on the nature of substance.
  • Vapour pressure does not depend on the quantity of the liquid taken and the surface area of the liquid.
  • Vapour pressure is not a colligative property & is independent of the concentration of the liquid.
Which of the following forms ideal solution?
  • $$C_6H_5Cl-C_6H_5Br$$
  • $$C_6H_6-C_6H_5CH_3$$
  • Hexane-heptane
  • none of these
Deliquescent substances absorb moisture from the air & changes into a solution.
  • True
  • False
The air in a room has 15 gm of water vapour per cubic meter of its volume. However the saturation of one cubic meter of volume requires 20gm of water vapour then relative humidity is :
  • $$50$$%
  • $$75$$%
  • $$20$$%
  • $$25$$%
For an ideal binary liquid system :
  • the change in temperature $$(\Delta H)$$ is zero
  • Raoult's law is obeyed
  • change in volume $$(\Delta V)$$ is zero
  • none of the above
Which of the following statements are correct for van't Hoff's factor 'i' for a solution of weak electrolytes $$A_xB_y$$?
  • $$i=1-\alpha+X\alpha+Y\alpha$$
  • i > 1 at normal dilution
  • i increases more rapidly with dilution and attains a limiting value of (x+y) at infinite dilution
  • the increases in 'i' with dilution is due to increase in molality of solution with dilution
On mixing 10 mL of carbon tetrachloride with 10 mL of benzene the total volume of the solution is :
  • $$> 20$$ mL
  • $$< 20$$ mL
  • $$= 20$$ mL
  • cannot be predicted
The Van't Hoff factor of very dilute solution of $$Ca{(N{O}_{3})}_{2}$$ is: 
  • 1
  • 2
  • 3
  • 4
Vapour pressure of a solvent containing nonvolatile solute is_________.
  • more than the vapour pressure of a solvent
  • less than the vapour pressure of solvent
  • equal to the vapour pressure of solvent
  • none
Which pair(s) of liquids on mixing is/are expected to show no net volume change and no heat effect?
  • Acetone and ethanol.
  • Chlorobenzene and bromobenzene.
  • Chloroform and benzene.
  • n-Butyl chloride and n-butyl bromide
A mixture of benzene and toluene forms :
  • An ideal solution
  • Non-ideal solution
  • Suspension
  • Emulsion
Which of the following form is an ideal solution?
  • Ethyl bromide + Ethyl iodide
  • Ethyl alcohol + Water
  • Chloroform + Benzene
  • Benzene + Toluene
An aqueous solution of methanol in water has vapour pressure:
  • equal to that of water
  • equal to that of methanol
  • more than that of water
  • less than that of water
The Van't Hoff factor of $$NaCl$$ assuming 100% dissociation is :
  • $$1/2$$
  • $$2$$
  • $$1$$
  • $$3$$
The ratio of the value of any colligative property for KCl solution to that of sugar solution is:
  • 1
  • 0.5
  • 2
  • 4
Each pair forms ideal solution except :
  • $${C}_{2}{H}_{5}Br$$ and $${C}_{2}{H}_{5}I$$
  • $${C}_{6}{H}_{5}Cl$$ and $${C}_{6}{H}_{5}Br$$
  • $${C}_{6}{H}_{6}$$ and $${C}_{6}{H}_{5}C{H}_{3}$$
  • $${C}_{2}{H}_{6}I$$ and $${C}_{2}{H}_{5}OH$$
The vapour pressure of a dilute solution of a solute is not influenced by:
  • temperature of solution
  • melting point of solute
  • mole fraction of solute
  • degree of dissociation of solute
Which of the following conditions is not correct for ideal solution 
  • no change in volume on mixing
  • no change in enthalpy on mixing
  • it obeys Raoults law
  • lonisation of solute should occurs to a small extent
The relative lowering in vapour pressure is proportional to
  • $$ X_{solute}$$
  • $$\frac {1}{X_{solute}}$$
  • $$\,\,\, m$$
  • None of the above
If in solvent, n simple molecules of solute combine to form an associated molecule, $$x$$ is degree of association the Van't Hoff's factor $$'i'$$ is equal to:
  • $$\;\displaystyle\frac{1}{1-nx}$$
  • $$\;\displaystyle\frac{1-x+nx}{1}$$
  • $$\;\displaystyle\frac{1-x+\displaystyle\frac{x}{n}}{1}$$
  • $$\;\displaystyle\frac{\displaystyle\frac{x}{n}-1+x}{1}$$
The Van't Hoff factors $$i$$ for an electrolyte which undergoes dissociation and association in solvents are respectively:
  • greater than one and less than one
  • less than one and greater than one
  • less than one and less than one
  • greater than one and greater than one
The boiling point of $$C_6H_6, CH_3OH, C_6H_5NH_2\,\, and \,\,C_6H_5NO_2 \,\,are\,\, 80^o C, 65^o C, 184^o C \,\,and \,\,212^o C$$ respectively. Which will show highest vapour pressure at room temperature:
  • $$C_6H_6$$
  • $$CH_3OH$$
  • $$C_6H_5NH_2$$
  • $$C_6H_5NO_2$$
In which of the following, the van't Hoff factor (i) is equal to one?
  • $$NaCl$$
  • $$KNO_3$$
  • $$Urea$$
  • All of these
Which compound corresponds van't Hoff factor (i) to be equal to 2 in dilute solution:
  • $$K_2SO_4$$
  • $$NaHSO_4$$
  • Sugar
  • $$MgSO_4$$
Addition of non-volatile solute to water always lowers its vapour pressure.
  • True
  • False
The Van't Hoff factor ($$i$$) for $${Na}_{2}S{O}_{4}$$ is:
  • 3
  • 2
  • 1
  • 0
A solution of benzene and toluene is an example of ________ solution.
  • Ideal
  • non ideal
  • azeotrope
  • none
The Van't Hoff factor of sulphur solution is _________ .
  • i =1
  • i =1/6
  • i =1/2
  • i =1/8
The ratio of the value of any colligative property for $$Ba{Cl}_{2}$$ solution to that for urea solution under similar condition is:
  • 2
  • 3
  • 1
  • 4
The van't Hoff factor for a solute which does not dissociate or associate in solution is:
  • 0
  • 2
  • 3
  • 1
Among $$0.1\:M$$ solutions of $$NaCl,\:CaCl_2\:and\:Al_2(SO)_3$$, the one with highest vapour pressure is:
  • $$NaCl$$
  • $$CaCl_2$$
  • $$Al_2(SO)_3$$
  • All have equal vapour pressure
A $$0.1\:molar$$ solution of $$NaCl$$ is found to be isotonic with $$1\%$$ urea solution. Calculate
(a) Van't Hoff factor
(b)Degree of dissociation of sodium chloride.
Assume density of $$1\%$$ urea equal to $$1\:g\:cm^{-3}$$.
  • $$\;$$(a)$$\;1.667,$$ (b)$$\;0.667$$
  • $$\;$$(a)$$\;1.82,$$ (b)$$\;0.69$$
  • $$\;$$(a)$$\;2.01,$$ (b)$$\;0.78$$
  • $$\;$$(a)$$\;2.12,$$ (b)$$\;0.94$$
At $$283K$$ a saturated solution of solid X can be prepared by dissolving $$21.0$$g of it in $$100$$g of water. The maximum amount of X which can be dissolved in $$100$$g of water at $$313K$$ is $$62.0$$g. An attempt is made to dissolve $$50.0$$g of X in $$100$$g of water at $$313K$$.
$$1$$. All the $$50.0$$g of X will dissolve at $$313K$$
$$2$$. At $$313K$$ $$29.0$$g of X will remain undissolved
$$3$$. Solubility of X decreases with an increase of temperature
$$4$$. On cooling the solution of X from $$313K$$ to $$283$$K more than $$21.0$$g of X will crystallize out.

Which of the above statements are correct?
  • $$1$$ and $$2$$
  • $$1$$ and $$4$$
  • $$2$$ and $$3$$
  • $$1,3$$ and $$4$$
The boiling point of $$C_{6}H_{6},\:CH_{3}OH,\:C_{6}H_{5}NH_{2}$$ and $$C_{6}H_{5}NO_{2}$$ are $$80\ ^{\circ}C$$, $$65\ ^{\circ}C$$, $$184\ ^{\circ}C$$ $$212\ ^{\circ}C$$ respectively. 
Which will show the highest vapour pressure at room temperature?
  • $$C_{6}H_{6}$$
  • $$CH_{3}OH$$
  • $$C_{6}H_{5}NH_{2}$$
  • $$C_{6}H_{5}NO_{2}$$
At $$20^0C$$, 36 g of sodium chloride can be dissolved in 100 g water. At $$80^0C$$, how many grams of sodium chloride can be dissolved in 100 g of water?
  • 35 g
  • 9 g
  • 37 g
  • 36 g
For electrolytic solution, the Van't Hoff factor (i) is always equals to unity.
  • True
  • False
In which of the following solvents, should $$KBr$$ be soluble at $$25^{\circ}C$$ ($$D$$ is the dielectric constant)?
  • $$C_{6}H_{6}(D=0)$$
  • $$CH_{3}OH(D=32)$$
  • $$(CH_{3})_{2}CO(D=21)$$
  • $$CCl_{4}(D=0)$$
The Van't Hoff factor (i) for $${K}_2SO_{4}$$ is ............... .
  • 1
  • 2
  • 0
  • 3
State True or False.
In association of solute, the Van't Hoff factor is greater than unity.
  • True
  • False
The Vant Hoff factor (i) for a dilute solution of $$K_{3}[Fe(CN)_{6}]$$ is (Assuming $$100\%$$ ionsation):
  • $$10$$
  • $$4$$
  • $$5$$
  • $$0.25$$
Solubility of a gas in a liquid increases on:
  • increasing temperature.
  • decreasing pressure.
  • increasing pressure.
  • increasing temperature and pressure.
Van't Hoff factor is:
  • $$\text{more than one in case of association}$$
  • $$\text{less than one in case of dissociation}$$
  • $$\dfrac {\text {normal molecular mass}}{\text {observed molecular mass}}$$
  • $$\dfrac {\text {observed molecular mass}}{\text {normal molecular mass}}$$
A drop each of two non-corrosive and nonirritating liquids $$A$$ and $$B$$ at a temperature of $$22^oC$$ are placed on the skin. Liquid $$A$$ gives a more cooling sensation than liquid $$B$$. Which of the following can be said about the liquids $$A$$ and $$B$$?
  • Liquid $$A$$ has higher boiling point than that of liquid $$B$$
  • Liquid $$A$$ has higher latent heat of vaporisation than that of liquid $$B$$
  • Liquid $$A$$ has lower latent heat of vaporisation than that of liquid $$B$$
  • The boiling points of liquid $$A$$ and $$B$$ are equal
Assertion: Wet air is heavier than dry air.
Reason: The density of dry air is more than density of water.
  • If both assertion and reason are true and the reason is a correct explanation of the assertion.
  • If both assertion and reason are true, but reason is not a correct explanation of the assertion.
  • If the assertion is true, but reason is false.
  • If both the assertion and reason are false.
  • If the assertion is false, but the reason is true.
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