CBSE Questions for Class 12 Engineering Chemistry Solutions Quiz 9 - MCQExams.com

$$ H_{2}O_{2} $$ used in rockets has the concentration
  • 50%
  • 70%
  • 30%
  • 90%
The Van't Hoff factor for sodium phosphate would be:
  • $$1$$
  • $$2$$
  • $$3$$
  • $$4$$
Van't Hoff factor of $$Ca(NO_3)_2$$ is:
  • $$1$$
  • $$2$$
  • $$3$$
  • $$4$$
Which of the following has highest percentage of hydrogen? 
  • $$CH_4$$
  • $$C_2H_4$$
  • $$C_6H_6$$
  • $$C_2H_2$$
When a substance is dissolved in a solvent, the vapour pressure of the solvent is decreased. This results in
  • An increase in the boiling point of the solution
  • A decrease in the boiling point of solvent
  • The solution having a higher freezing point than the solvent
  • The solution having a lower osmotic pressure than the solvent
The Van't Hoff factor, i for a $$0.2$$ molal aqueous solutions of urea is:
  • $$0.2$$
  • $$0.1$$
  • $$1.2$$
  • $$1.0$$
Which of the following factor(s) affect the solubility of a gaseous solute in the fixed volume of liquid solvent?
(a) nature of solute (b) temperature (c) pressure
  • (a) and (c) at constant T
  • (a) and (b) at constant P
  • (b) and (c) only
  • (c) only
Intermolecular forces between two benzene molecules are nearly of same strength as those between two toluene molecules. For a mixture of benzene and toluene, which of the following are not true?
  • $$\Delta_{mix} H = zero$$
  • $$\Delta_{mix} V = zero$$
  • These will form minimum boiling azeotrope.
  • These will not form ideal solution.
For  a binary ideal solution, the variation in total vapour pressure versus composition of solution is given by which of the curves?
Solutions are:
  • heterogeneous mixtures.
  • compounds.
  • homogeneous mixtures.
  • elements.
The correct solubility order is/are :
(I) $$CaCO_3 > SrCO_3 > BaCO_3$$ 
(II) $$Li_2CO_3 < Na_2CO_3 < K_2CO_3$$ 
(III) $$K_2CO_3 < Rb_2CO_3 < Cs_2CO_3$$ 
(IV) $$Na_2CO_3 > K_2CO_3 > Rb_2CO_3$$
  • II, IV
  • I, IV
  • II, III, IV
  • I, II, III
A saturated solution of a salt in water can be made unsaturated by:
  • Heating 
  • Cooling 
  • Evaporation 
  • Distillation 
The solubility of $$Na_2SO_4, \ BeSO_4, \ MgSO_4$$ and $$BaSO_4$$ in water follow the order:
  • $$BaSO_4 > BeSO_4 > MgSO_4 > Na_2SO_4$$
  • $$Na_2SO_4 > BeSO_4 > MgSO_4 > BaSO_4$$
  • $$BeSO_4 > MgSO_4 > BaSO_4 > Na_2SO_4$$
  • $$MgSO_4 > BeSO_4 > Na_2SO_4 > BaSO_4$$
$$X, Y$$ and $$Z$$ In the above graph are 
1845539_7047fb73eec34bb394f91f1ccc4e492b.PNG
  • $$X= p_1 + p_2, Y =1 , Z = 0$$
  • $$X= p_1 + p_2, Y =0, Z = 1$$
  • $$X= p_1 + p_2, Y =0, Z = 1$$
  • $$X= p_1 + p_2, Y =1, Z = 0$$
What is the mass percentage of carbon tetrachloride if $$22 g$$ of benzene is dissolved in $$122$$ $$g$$ of carbon tetrachloride? 
  • 84.72 %
  • 1528 %
  • 50 %
  • 44%
Directions : In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as :
Assertion : Pressure does not have any effect on solubility of solids in liquids.
Reason : Solids and liquids are highly incompressible.
  • 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.
Which of the following statement is not correct?
  • 5% aqueus solutions of $$NaCl$$ and $$KCl$$ are said to be isomolar
  • 1 M sucrose solution and 1 M glucose solution are isotonic
  • Molecular mass of acetic acid and benzoic acid is higher than normal mass in cryoscopic methods
  • For the same solution $$\cfrac{\Delta T_b}{\Delta T_f}=\cfrac{K_b}{K_f}$$
Mixing an acid or base with water results in a decrease in the concentration of ions ($$H_3O^+$$/$$OH^-$$ ) per unit volume. Such a process is called?`
  • Neutralisation
  • Reaction
  • Dilution
  • Saturation
Dry air is first passed through a 0.1M $$KCl$$ in water & then through 6M $$KCl$$ solution. Which among the following statements is/are true :
(i) Dilute solution will show a loss in weight.
(ii) Dilute solution will show a gain in weight.
(iii) Change in weight of the dilute solution is proportional to its vapour pressure.
(iv) Concentrated solution will show a gain in weight.
(v) Change in weight of the concentrated solution is proportional to its vapour pressure.
  • i
  • ii
  • iii
  • iv
  • v
In which case van't Hoff factor is maximum (assuming no hydrolysis)?
  • $$KCl$$, 50% ionised
  • $$K_2SO_4$$, 40% ionised
  • $$FeCl_3$$, 30% ionised
  • $$SnCl_4$$, 20% ionised
For 1 M solution of HA, the dissociation constant $$K_a$$ in terms of vant Hoff factor (i) can be written as :
  • $$\dfrac{(i-1)^2}{i}$$
  • $$\dfrac{(i+1)^2}{i}$$
  • $$\dfrac{i}{(i-1)^2}$$
  • $$\dfrac{(i-1)^2}{(2-i)}$$
The diagram below shows the ln(P$$_{vapour}$$) vs. 1/T for four substances. The Clausius Clapeyron equation describes this relationship.
The Clausius-Clapeyron equation is :

   $$ln (P_{vapour}) = - \dfrac{\Delta H_{vapour}}{R}\left [ \dfrac{1}{T} \right ]+C$$

According to the graph, at high temperatures, which substance has the greatest vapour pressure?

72198.jpg
  • W
  • X
  • Y
  • Z
For a binary ideal liquid solution, the variation in total vapour pressure versus composition of solution is given by which of the curves?
Number of non-linear plots among the following are :
  • vapour pressure of pure liquid v/s temperature
  • vapour pressure of pure liquid v/s its mass
  • vapour pressure of pure liquid v/s its mole fraction in ideal solution
  • vapour pressure of liquid v/s its mole fraction in non-ideal solution showing positive deviation
The freezing point depression constant for water is $$-1.86^{0}C m^{-1}.$$ If 5.00 g $$Na_2SO_4$$ is dissolved in 45.0 g $$H_2O,$$ the freezing point is changed by $$3.82^0C.$$ 
Calculate the vant Hoff factor for $$Na_2SO_4.$$
  • $$2.05$$
  • $$2.63$$
  • $$3.11$$
  • $$0.381$$
A zinc metal sample containing zinc chloride as impurity was made to react with an excess of dilute hydrochloric acid at $$ 27^{o}C$$. Liberated hydrogen gas is collected at 760 mm Hg pressure that occupies $$780.0 cm^{3}$$ volume. If the vapour pressure of water at $$27^{o}C$$ is 14 mm Hg, what is the volume of $$H_{2}$$ at STP? The Standard pressure is 760 mm Hg (molar volume of gas at standard temperature and pressure, $$STP = 22.4 dm^{3}$$)
  • $$746 cm^{3}$$
  • $$697 cm^{3}$$
  • $$750 cm^{3}$$
  • $$300 cm^{3}$$
Benzene and naphthalene form an ideal solution at room temperature. For this process, the true statement(s) is(are):
  • $$\Delta G$$ is positive
  • $$\Delta S_{system}$$ is positive
  • $$\Delta S_{surroundings}=0$$
  • $$\Delta H=0$$
A 0.001 molal solution of $$[Pt (NH_{3})_{4} Cl_{4} ]$$ in water has a freezing point depression of $$0.0054^{0}C$$. If $$K_{f}$$ for water is 1.80 K.kg.mol$$^{-1}$$, the correct formulation of the above molecule is:
  • $$[Pt (NH_{3})_{4} Cl_{3} ]Cl$$
  • $$[Pt (NH_{3})_{4} Cl_2 ]Cl_{2}$$
  • $$[Pt (NH_{3})_{4} Cl_2 ]Cl_{3}$$
  • $$[Pt (NH_{3})_{4} Cl_{4} ]$$
Three different solutions are prepared by adding 'w' gm of 'A' into 1 kg of water, 'w' gm of 'B' into another 1 kg of water and 'w' gm of 'C' in another 1 kg of water (A, B, C are non electrolytic). Dry air is passed over these solutions in sequence $$(A\rightarrow B\rightarrow C)$$. The loss in weight of solution A was found to be 2 gm while solution B gained 0.5 gm and solution C lost 1 gm. Then the relation between molar masses of A, B and C is/are :
  • $$M_A:M_B:M_C=4:3:5$$
  • $$M_A:M_B:M_C=\dfrac {1}{4}:\dfrac {1}{3}:\dfrac {1}{5}$$
  • $$M_C > M_A > M_B$$
  • $$M_B > M_A > M_C$$
Which of the following plot does not represent the behaviour of an ideal binary liquid solution of $$A$$ and $$B$$?
  • Plot of $$p_A$$ vs x$$_A$$ is linear
  • Plot of $$ p_B$$ vs x$$_B$$ is linear
  • Plot of $$p_{total}$$ vs x$$_A$$ is linear
  • Plot of $$p_{total}$$ vs x$$_B$$ is parabola
Choose the correct statement with respect to the vapour pressure of a liquid among the following.
  • Increases linearly with increasing temperature.
  • Increases non-linearly with increasing temperature.
  • Decreases linearly with increasing temperature.
  • Decreases non-linearly with increasing temperature.
An ideal binary solution is prepared by two liquids A and B, with p$$^o_A$$ > p$$^o_B$$. Then :
  • A-B interactions are stronger than A-A and B-B
  • A and B have same molecular masses
  • A-B interactions are similar to A-A and B-B interactions
  • Both A and B are non-polar substances
To determine the solubility of a solute in water, a solution must be prepared that is___________.
  • saturated
  • unsaturated
  • concentrated
  • supersaturated
The observed osmotic pressure for a 0.10 M solution of $$Fe(NH_4)_2(SO_4)_2$$ at $$25^oC$$ is 10.8 atm. The expected and experimental (observed) values of Van't Hoff factor (i) will be respectively:

 $$[R=0.082\ L\ {atm} K^{-1} mol^{-1}]$$
  • $$5$$ and $$4.42$$
  • $$4$$ and $$4.00$$
  • $$5$$ and $$3.42$$
  • $$3$$ and $$5.42$$
In which of the following pairs of solutions will the values of the Van't Hoff factor be the same?
  • $$0.05 M K_4[Fe(CN)_6]$$ and $$0.10 M FeSO_4$$
  • $$0.10 M K_4[Fe(CN)_6]$$ and $$0.05 M FeSO_4(NH_4)_2SO_4.6H_2O$$
  • $$0.20 M NaCl$$ and $$0.10 M BaCl_2$$
  • $$0.05 M FeSO_4(NH_4)_2SO_4.6H_2O$$ and $$0.02MKCl. MgCl_2. 6H_2O$$
The ratio of the actual value of a colligative property to the value calculated, assuming the substance to be a nonelectrolyte, is referred to as ..................
  • Henry's law
  • vapor pressure lowering
  • the van't Hoff factor
  • freezing point depression
  • osmotic pressure
For an ideal solution of two components A and B, which of the following is true?
  • $$\Delta H_{mixing} < 0(zero)$$
  • $$\Delta H_{mixing} > 0(zero)$$
  • A - B interaction is stronger than A - A and B - B interactions
  • A - A, B - B and A - B interactions are identical
State True or False.

For a solution of $$Al{Cl}_{3}$$ in water, the Van't Hoff factor (i) is greater than 1.
  • True
  • False
Raoult's law is obeyed by each constituent of a binary liquid solution when :
  • the forces of attractions between like molecules are greater than those between unlike molecules
  • the forces of attractions between like molecules are smaller than those between unlike molecules
  • the forces of attractions between like molecules are identical with those between unlike molecules
  • the volume occupied by unlike molecules are different
Which of the following represent(s) correctly the changes in thermodynamic properties during the formation of 1 mole of an ideal binary solution?
$$i.$$  $$NaN{O}_{3}$$                                             
$$ii.$$ $$Ba{Cl}_{2}$$
$$iii.$$ $${K}_{3}[Fe{(CN)}_{6}]$$                             
$$iv.$$ $${C}_{6}{H}_{12}{O}_{6}$$
Increasing order of Van't Hoff factor is:
  • $$(iv)<(ii)<(i)<(iii)$$
  • $$(iv)>(ii)>(i)>(iii)$$
  • $$(iv)<(iii)<(ii)<(i)$$
  • $$(iv)<(i)<(ii)<(iii)$$
Which salt may show the same value of van't Hoff factor (i) as that of $$K_4Fe(CN)_6$$ in very dilute solution state?
  • $$Al_2(SO_4)_3$$
  • $$NaCl$$
  • $$Al(NO_3)_3$$
  • $$Na_2SO_4$$
The vapour pressure of a certain liquid is given by the equation:
$$log_{10}P=3.54595+\dfrac {313.7}{T}+1.40655 log_{10}T$$, where, P is the vapour pressure in mm and T is temperature in K. The molar latent heat of vaporisation as a function of temperature and  its value in cal at 80 K is :
  • $$597$$
  • $$778.56$$
  • $$1056.24$$
  • $$1194$$
Let the solubilities of $$AgCl$$ in $${H}_{2}O$$, $$0.01M$$ $$Ca{Cl}_{2}$$, $$0.01M$$ $$NaCl$$ and $$0.05M$$ $${Ag}{NO}_{3}$$ be $${s}_{1},{s}_{2},{s}_{3}$$ and $${s}_{4}$$ respectively. What is the correct relationship between these quantities?
  • $${s}_{1}> {s}_{2}> {s}_{3}> {s}_{4}$$
  • $${s}_{1}> {s}_{2}= {s}_{3}> {s}_{4}$$
  • $${s}_{1}> {s}_{3}> {s}_{2}> {s}_{4}$$
  • $${s}_{4}> {s}_{2}> {s}_{3}> {s}_{1}$$
Comprehension # 2
Following passage explains the effect of temperature on the vapour pressure of the liquid. 

Effect of temperature on vapour pressure
The quantity of heat required to evaporate a given liquid at constant temperature is defined as the heat of vaporisation. Variation of vapour pressure with temperature is given by,

Clausius-Clapeyron equation.

$$\;\;\;\;\;\;\;\;\;\;\;\;log_e\:P\,=\,\displaystyle-\frac{\Delta H_{vap}}{RT}+log_e\,A$$

A liquid is said to be at its boiling temperature if its vapour pressure is equal to external pressure. Therefore, the boiling point of water in particular and of liquids in general decreases as an altitude of a place increases  where the external pressure is less than $$1\: atmosphere$$ (normal b.p. of water is $$373.15\: K$$ at $$1\: atmosphere$$)

On top of mount everest, for example, where the atmospheric pressure is only about $$260\:mm\: Hg$$, water boils at approximately $$71^{\circ}C$$. Conversely, if the external pressure on a liquid is greater than $$1\:atm$$, the vapour pressure necessary for boiling than normal boiling is reached later, and the liquid boils at a temperature greater than the normal boiling point.

Clausius-Clapeyron equation can be written in the following form:
  • $$\;P\,=\,Ae^{-\Delta H_{vap}/RT}$$
  • $$\;\displaystyle\dfrac{d\,log_{10}P}{d\,T}\,=\,\displaystyle\dfrac{\Delta H_{vap}}{2.303RT^2}$$
  • $$\;\displaystyle\dfrac{dlog_eP}{d\,T}\,=\,\displaystyle-\dfrac{\Delta H_{vap}}{RT^2}$$
  • $$\;P\,=\,Ae^{\Delta H_{vap}/RT}$$
The van't Hoff factor for $$HF_{aq.}$$ is 2
  • True
  • False
The vapour pressures of two liquids A and B in their pure states are in the ratio of 1 :A binary solution of A and B contains A and B in the mole proportion of 1 :The mole fraction of A in the vapour phase of the solution will be:
  • $$0.33$$
  • $$0.2$$
  • $$0.25$$
  • $$0.52$$
Van't Hoff factor of centimolal solution of $$K_3[Fe(CN)_6]$$ is 3.Calculate the percent dissociation of $$K_3[Fe(CN)_6]$$.
  • 33.33
  • 0.78
  • 78
  • 23.33
The solubility of gas in liquid is directly proportional to the pressure over the solutions at a given temperature.
  • True
  • False
At same temperature which pair of the following solutions are isotonic?
  • $$0.2M$$ $$BaCl_2$$ and $$0.2M$$ urea
  • $$0.1M$$ urea and $$0.1M$$ NaCl
  • $$0.1M$$ NaCl and $$0.1M$$ $$K_2SO_4$$
  • $$0.1M$$ $$Ba(NO_3)_2$$ and $$0.1M$$ $$Na_2SO_4$$
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