CBSE Questions for Class 12 Engineering Chemistry Solutions Quiz 4 - MCQExams.com

When $$1$$ mole of a substance is present in $$1$$ L of the solution, it is known as :
  • normal solution
  • molar solution
  • molal solution
  • None of the above
Van't Hoff factor of $$0.01M$$ $$Ba{Cl}_{2}$$ is $$1.98$$, percentage dissociation of $$Ba{Cl}_{2}$$ on this concentration will be:
  • $$69$$
  • $$100$$
  • $$49$$
  • $$98$$
What is the effect of temperature on solubility of a gas?
  • Solubility of a gas increase with rise in temperature
  • Solubility of a gas decreases with rise in temperature
  • No effect
  • Sometimes increases with increase in temperature, sometimes decreases
If solubility is not changing as the temperature increases then which graph is solubility curve of the substance?
The following substances were all dissolved in 100 grams of water at 290 K to produce saturated solutions.If the solution is heated to 310 K, which substance will have a decrease in its solubility:
  • $$NaCI$$
  • $$KI$$
  • $$CaCl_2$$
  • $$HCI$$
  • $$KNO_3$$
Which of the following is not miscible in alcohol?
  • Water
  • Petrol
  • Diesel
  • Kerosene
The solubility of a solute indicates :
  • the temperature of the solution
  • the quantity of solvent
  • the quantity of solute
  • the nature of the solute and solvent
  • all of these
At equilibrium, the rate of dissolution of a solid solute in a volatile liquid solvent is:
  • less than the rate of crystallisation
  • greater than the rate of crystallisation
  • equal to the rate of crytallisation
  • zero
A closed vessel is maintained at a constant temperature. It is first evacuated and then vapour is injected into it continuously. The pressure of the vapour in the vessel is:
  • increases continuously
  • first increases and then remains constant
  • first increases and then decreases
  • none of the above
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
Hydrogen gas adsorbed on surface of platinum is an example of solid in gas solution.
  • True
  • False
Which of the following is a possible source of error in the results of this experiment?
524223_36298f57589f4772952ec05e1b2c5e37.png
  • Inaccurate weighing of the isopropanol
  • The presence of bits of broken glass in the flask
  • Failure to correct for humidity
  • Misreading of the atmospheric pressure
The initial pressure inside the flask is:
524221_18c042995fb147b9a377600f147d827d.png
  • near zero (vacuum)
  • $$27\ mm\ $$$$\displaystyle Hg$$
  • $$760\ mm\ $$$$\displaystyle Hg$$

  • $$(760-27)\ mm\ Hg $$

Which of the following salt has the same value of Van't Hoff factor i as that of $$K_3 [Fe(CN)_6]$$?
  • $$Al_2(SO_4)_3$$
  • $$NaCl$$
  • $$Na_2SO_4$$
  • $$Al(NO_3)_3$$
Which of the following is a true solution?
  • $$NaCl$$ is sulphur dioxide
  • Copper in silver
  • Salt in petrol
  • Mud in water
Identify which of the following statements is FALSE?
  • The vapor pressure of a liquid decreases with increasing atmospheric pressure.
  • The value of an equilibrium constant is dependent on temperature.
  • The rate of a spontaneous reaction cannot be determined solely by its Gibbs free energy.
  • During a phase transition, the temperature of a substance must be constant.
  • The addition of a catalyst to a reaction at equilibrium has no net effect on the system.
In which of the following solvent, the solubility of $$NaCl$$ is maximum ?
  • Methanol
  • Water
  • Formic acid
  • Formamide
The mass of a non-volatile solute of molar mass 40 g $$mol^{-1}$$ that should be dissolved in 114 g of octane to lower its vapour pressure by 20% is :
  • 10 g
  • 11.4 g
  • 9.8 g
  • 12.8 g
Which of the following equation does NOT correctly depict the process by which the given solute dissolves in water?
  • Solid calcium nitrate is added to water to form an aqueous solution.

    $$Ca(NO_{3})_{2}(s) \rightarrow Ca^{2+} + 2NO_{3}$$$$^{-}(aq)$$
  • Magnesium hydroxide, a very slightly soluble solid, is dissolved in water.

    $$Mg(OH)_{2}(s)\rightarrow Mg^{2+}(aq) + 2OH^{-}(aq)$$
  • Sucrose, table sugar, $$C_{12}H_{22}O_{11}$$, dissolves in water.

    $$C_{12}H_{22}O_{11}(s) \rightarrow C_{12}H_{22}O_{11}(aq)$$
  • Phosphoric acid, a weak triprotic acid, dissolves in water.

    $$H_{3}PO_{4}(l)\rightarrow 3H^{+}(aq) + PO_{4}^{3-}(aq)$$
Which of these is a colligative property of a solution?
  • Relative lowering of vapour pressure
  • Elevation of boiling point
  • Depression of freezing point
  • Osmotic pressure
Which of the following solutions does not  show positive deviation? 
  • Acetone and Ethanol
  • Toluene and Benzene
  • Water and Ethanol
  • Water and Methanol
The van't Hoff factor of acetic acid solution is __________ than one and the value of normal colligative property is __________ than the observed colligative property of this solution.
  • more, less
  • less, more
  • less, less
  • more, more
Volume of mixing for a liquid solution is :
  • may be positive or negative depending on the nature of liquids
  • 0
  • +ve
  • -ve
Which of the following sentences is true?
  • Relative lowering of vapor pressure of an ideal solution containing a non-volatile solute is equal to the mole fraction of the solute at a given temperature
  • Relative lowering of vapor pressure of an ideal solution containing a non-volatile solute is equal to the mole fraction of the solvent at a given temperature
  • Relative lowering of vapor pressure of an ideal solution containing a non-volatile solute depends on the nature of the solute at a given temperature
  • Relative lowering of vapor pressure of an ideal solution containing a non-volatile solute depends on the nature of the solvent at a given temperature
$$3 $$ gms of urea is dissolved in $$45 $$ gms of $${H}_{2}O$$. The relative lowering in vapour pressure is :
  • $$0.05$$
  • $$0.04$$
  • $$0.02$$
  • $$0.01$$
In an endothermic process, solubility increases with ______ in temperature.
  • increase
  • decrease
  • remains same
  • none of the above
The correct value for the relative lowering of vapour pressure of a very dilute solution is equal to:
  • mole fraction of solute
  • mole fraction of solvent
  • ratio of moles of solute to moles of solvent
  • ratio of moles of solvent to moles of solute
When heating of a miscible solution begins, vapours formed will be:
  • of liquid lower in boiling point
  • of liquid higher in boiling point
  • of both liquids with a higher concentration of liquid having low boiling point
  • None of the above
Which of the following will change the relative lowering of vapour pressure of a solution?
  • Chemical properties of solute
  • Amount of solvent
  • Amount of solute
  • All of these
Relative lowering of vapour pressure of a solution is equal to:
  • the mole fraction of solvent
  • the ratio of moles of solute to moles of solvent
  • the mole fraction of solute
  • the ratio of moles of solvent to moles of solute
The equation that represents van't Hoff general solution equation is :
  • $$\pi = \dfrac{n}{V}RT$$
  • $$\pi = nRT$$
  • $$\pi = \dfrac{V}{n}RT$$
  • $$\pi = nVRT$$
A student slowly mixes salt into 25 ml of water until no more salt dissolves in it. The student could make more salt dissolve in the solution by:
  • cooling it
  • evaporating it
  • heating it
  • stirring it
At $$283 K$$ 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 $$313 K$$ is $$62.0 g$$. An attempt is made to dissolve $$50.0 g$$ of $$X$$ in $$100 g$$ of water at $$313 K$$.

A. All the $$50.0 g$$ of $$X$$ will dissolve at $$313 K$$
B. At $$313 K$$ $$29.0 g$$ of $$X$$ will remain undissolved
C. Solubility of $$X$$ decreases with increases of temperature
D. On cooling the solution of $$X$$ from $$313 K$$ to $$283 K$$ more than $$21.0 g$$ of $$X$$ will crystallize out.

Which of the above statements are correct?
  • A and B
  • A and D
  • B and C
  • A, C and D
Assuming ideal behaviour, the enthalpy and volume of mixing of two liquids, respectively, are:
  • zero and zero
  • +ve and zero
  • -ve and zero
  • -ve and -ve
The value of van't Hoff factor for $$0.1$$M $$Ba(NO_3)_2$$ solution is $$2.74$$. The degree of dissociation is:
  • $$100\%$$
  • $$92\%$$
  • $$87\%$$
  • $$74\%$$
For a non-volatile solute:
  • vapour pressure of solution is more than vapour pressure of solvent
  • vapour pressure of solvent is zero
  • vapour pressure of solute is zero
  • all of the above
The pair of boiling point and compound are given as,

$$C_6 H_6,$$      $$CH_3OH$$     $$C_6H_5NO_2$$     $$C_6H_5NH_2$$
 $$80^oC$$          $$65^oC$$          $$212^oC$$               $$184^oC$$    
    (I)              (II)            (III)                  (IV)

Which will show lowest vapour pressure at room temperature?
  • $$C_6H_6$$
  • $$CH_3 OH$$
  • $$C_6H_5NO_2$$
  • $$C_6H_5NH_2$$
Vapour pressure of pure $$A(p^0_A)=100$$ mm Hg
Vapour pressure of pure $$B(p^0_B)=150$$ mm Hg

2 mole of liquid A and 3 mole of liquid B are mixed to form an ideal solution. The vapour pressure of the solution will be :
  • 135 mm
  • 130 mm
  • 140 mm
  • 145 mm
For which among the following equimolar aqueous solutions Van't Hoff factor has the lowest value? 
  • Aluminium Chloride
  • Potassium Sulphate
  • Ammonium Chloride
  • Urea
Following properties will decrease with increase in temperature except:
  • surface tension
  • viscosity
  • density
  • vapour pressure
6gm of urea is dissolved in 90gm of water. Relative lowering of vapour pressure is:
  • 0.02
  • 0.2
  • 0.002
  • 0.04
Mole fraction of the component A in vapour phase is $$x_1$$ and mole fraction of component A in liquid mixture is $$x_2$$, then ($$p^0_A =$$ vapour pressure of pure A; $$p^0_B =$$ vapour pressure of pure B), the total vapour pressure of liquid mixture is :
  • $$p^0_A\dfrac{x_2}{x_1}$$
  • $$p^0_A\dfrac{x_1}{x_2}$$
  • $$p^0_B\dfrac{x_1}{x_2}$$
  • $$p^0_B\dfrac{x_2}{x_1}$$
Which of the following will form an ideal solution?
  • $$C_2H_5OH$$ and water
  • $$HNO_3$$ and water
  • $$CHCl_3$$ and $$CH_3COCH_3$$
  • $$C_6H_6$$ and $$C_6H_5CH_3$$
The vapour pressure of pure benzene at $$88^oC$$ is 957 mm and that of toluene at the same temperature is 379.5 mm. Calculate the composition of benzene-toluene mixture boiling at $$88^oC$$.
  • $$x_{benzene}=0.66; \,x_{toluene}=0.34$$
  • $$x_{benzene}=0.34; \,x_{toluene}=0.66$$
  • $$x_{benzene} = x_{toluene}=0.5$$
  • $$x_{benzene}=0.75;\, x_{toluene}=0.25$$
At $$25^oC$$ the vapour pressure of pure benzene is 93.9 torr. When a nonvolatile solute is added to benzene, the vapour pressure of benzene is lowered to 91.5 torr. Calculate the mole fraction of the solute.
  • 0.974
  • 0.026
  • 0.034
  • 0.056
Van't Hoff factor of $$Hg_2Cl_2$$ in its aqueous solution will be ($$Hg_2Cl_2$$ is $$80\%$$ ionized in the solution):
  • $$1.6$$
  • $$2.6$$
  • $$3.6$$
  • $$4.6$$
$$3g$$ urea is dissolved in $$45g$$ of water. The relative lowering of vapour pressure is:
  • $$0.05$$
  • $$0.04$$
  • $$0.02$$
  • $$0.01$$
What is the vapour pressure of a solution of glucose which has an osmotic pressure of 3 atmospheres at $$20^C?$$ The vapour pressure of water at $$20^oC$$ is $$17.39 mm$$. Consider the density of solution equal to that of the solvent.
  • $$12.35 mm$$
  • $$14.35 mm$$
  • $$16.35 mm$$
  • $$17.35 mm$$
At $$25^oC$$, the vapour pressure of pure benzene is 100 torr, while that of pure ethyl alcohol is 44 torr. Assuming ideal behaviour, calculate the vapour pressure at $$25^oC$$ of a solution which contains 10 g of each substance.
  • 33.775 torr
  • 54.775 torr
  • 64.775 torr
  • 60.775 torr
Which of the following is not correct for an ideal solution?
  • Raoult's law is obeyed for entire concentration range and temperatures
  • $$\triangle H_{mix}=0$$
  • $$\triangle V_{mix}=0$$
  • $$\triangle S_{mix}=0$$
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