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

The reduction potential of hydrogen electrode will be positive if 
  • $${P_{{H_2}}} = 2\;atm;\left[ {H^ + } \right] = 1\;M$$
  • $${P_{{H_2}}} = 2.5\;atm;\left[ {H^ + } \right] = 1.5\;M$$
  • $${P_{{H_2}}} = 2.5\;atm;\left[ {H^ + } \right] = 1\;M$$
  • $${P_{{H_2}}} = 1\;atm;\left[ {H^ + } \right] = 2\;M$$
The vapour pressure of pure water at $$25^{\circ}C$$ is $$30\ mm$$. The vapour pressure of $$10\%\ (W/W)$$ glucose  solution at $$25^{\circ}C$$ is :
  • $$31.5\ mm$$
  • $$30.6\ mm$$
  • $$29.67\ mm$$
  • $$26.56\ mm$$
Relative decrease in vapour of an aqueous $${\text{NaCl}}$$ is $$0.167$$. Number of moles of $${\text{NaCl}}$$ present in $$180\ g$$ of $${{\text{H}}_{\text{2}}}{\text{O}}$$ is:
  • $$2\ {\text{mol}}$$
  • $$1\ {\text{mol}}$$
  • $$3\ {\text{mol}}$$
  • $$4\ {\text{mol}}$$
The vapour pressure of pure benzene at a certain temperature is 200 mm Hg. At the same temperature the vapour pressure of a solution containing 2 g of non volatile non electrolyte solid in 78 g of benzene is 195 mm Hg. What is the molecular mass of solid?
  • 50
  • 70
  • 85
  • 80
Which represents correct difference when non-volatile solute is present in an ideal solution?

1176978_1e9ef7f602744155bfd7adb76d1b26c3.png
  • $$ I, II ,III $$
  • $$ I, II $$
  • $$ II ,III $$
  • $$ I, II $$
Consider a binary mixture of volatile liquids. If at $$X_A=0.4$$ the vapour pressure of solution is $$580\ torr$$ then the mixture could be $$(p_{A}^{0}=300\ torr, p_{B}^{0}=800\ torr)$$
  • $$CHCl_3-CH_3COCH_3$$
  • $$C_6H_5Cl-C_6H_5Br$$
  • $$C_6H_6-C_6H_5CH_3$$
  • $$nC_6H_{14}-nC_7H_{16}$$
For a binary ideal liquid solution, the total vapour pressure of the solution is given as:
  • $${ P }_{ total }\quad =\quad { P }_{ A }^{ \circ }\quad +\quad \left( { P }_{ A }^{ \circ }\quad -\quad { P }_{ B }^{ \circ } \right) { X }_{ B }$$
  • $${ P }_{ total }\quad =\quad { P }_{ B }^{ \circ }\quad +\quad \left( { P }_{ A }^{ \circ }\quad -\quad { P }_{ B }^{ \circ } \right) { X }_{ A }$$
  • $${ P }_{ total }\quad =\quad { P }_{ B }^{ \circ }\quad +\quad \left( { P }_{ B }^{ \circ }\quad -\quad { P }_{ A }^{ \circ } \right) { X }_{ A }$$
  • $${ P }_{ total }\quad =\quad { P }_{ B }^{ \circ }\quad +\quad \left( { P }_{ B }^{ \circ }\quad -\quad { P }_{ A }^{ \circ } \right) { X }_{ B }$$
When non-volatile solute is added to a pure solvent, the 
  • vapour pressure of the solution becomes lower than the pressure of the pure solvent.
  • rate of evaporation of solvent is reduced
  • solute does not affect the rate of condensation
  • none of these
A mixture of $$KCl$$ and $$KClO_3$$ weighing $$1.8$$ gms was heated . After the reaction, the dry oxygen gas generated occupied $$140$$  ml at STP. What percent of original mixture was $$KClO_3$$?
  • $$28.4\%$$
  • $$37.5\%$$
  • $$42.6\%$$
  • $$64.8\%$$
Which of the following equimolar solution have highest vapour pressure?
  • Glucose
  • $$NaCl$$
  • $${ K }_{ 2 }{ SO }_{ 4 }$$
  • $${ K }_{ 4 }{ Fe(CN) }_{ 6 }$$
Calculate solubility (in moles / litre) of a saturated aqueous solution of $$Ag_3PO_4$$ if the vapour pressure of the solution becomes 750 torr at 373 K
(Assume molality=molarity).
  • $$2/15$$
  • $$1/30$$
  • $$10/54$$
  • $$20/27$$
18 g of glucose $${ (C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 })$$ is added to 178.2 g of water. The vapour pressure of water for this aqueous solution at $${ 100 }^{ \circ  }C$$ is ?
  • 7.60 Torr
  • 76.00 Torr
  • 752.40 Torr
  • 759.00 Torr
The solubility of a specific non-volatile salt is $$4g$$ in $$100g$$ of water at $$25^{\circ} C$$. If $$2.0g,4.0g$$ and $$6.0g$$ of the salt added of $$100g$$ of water at $$25^\circ C$$, in system X, Y and Z. The vapour pressure would be in the order:
  • $$X<Y<Z$$
  • $$X>Y>Z$$
  • $$Z>X>Y$$
  • $$X>Y=Z$$
Liquids $$A$$ and $$B$$ form an ideal solution. At $$30^o$$ C, the total vapour pressure of a solution containing $$1$$ mol of $$A$$ and $$2$$ mols of $$B$$ is $$250$$ mm $$Hg$$. The total vapour pressure becomes $$300$$ mm $$Hg$$ when $$1$$ more mol of A is added to the first solution. The vapour pressures of pure $$A$$ and $$B$$ at the same temperature are 
  • $$450, 150$$ mm $$Hg$$
  • $$150, 450$$ mm $$Hg$$
  • $$250, 300$$ mm $$Hg$$
  • $$125, 150$$ mm $$Hg$$
If '$$\alpha $$' is degree of dimerisation of $${ CH }_{ 3 }COOH$$ in benzene, then van't Hoff factor '$$i$$' for circulation of colligative properties is:
  • $$1+\alpha $$
  • $$1-\dfrac { \alpha }{ 2 } $$
  • $$1+\dfrac { \alpha }{ 2 } $$
  • $$1+2\alpha $$
A $$0.010 g$$ sample of $$\mathrm { Cr } \left( \mathrm { NH } _ { 3 } \right) _ { 4 } \left( \mathrm { SO } _ { 4 } \right) \mathrm { Cl }$$ is dissolved in $$25.0\mathrm { mL }$$ of water and the osmotic pressure of the solution is $$59.1 \ \text{torr}$$ at $$25 ^ { \circ } \mathrm { C }.$$ How many moles of ions are produced per mole of compound?
  • $$1$$
  • $$4$$
  • $$2$$
  • $$3$$
What is the molality of an aqueous solution,whose relative lowering of vapour pressure is 0.1
  • 2m
  • 2.75m
  • 3.25m
  • 5.56m
Which of the following is satisfied by an ideal solution?
  • Formation of an azeotropic mixture
  • $$ \Delta S_{mix} = 0$$
  • Raoult's law is obeyed under particular set of conditions only
  • $$  \Delta H_{mix} = 0$$
Solubility of NaOH in water:
  • increases with increase in temperature
  • decreases with increase in temperature
  • is not affected by a change in temperature
  • first increases and then decreases with temperature
Find the volume of gases evolved by passing  $$0.1 A$$  of current for  $$965s$$  through an aqueous solution of sodium succinate at  $$27 ^ { \circ }  { C }$$   $$\&$$  $$1atm$$. Assume  $$100\%$$ current efficiency  $$\&$$   $$22.4 { L }$$  volume of  $$1$$ mole of gas.
  • $$22.4 { mL }$$
  • $$44.8 { mL }$$
  • $$67.2 { mL }$$
  • $$49.23mL$$
How much water should be mixed with $$12\mathrm { mL }$$ of methanol to give a $$12\%$$ solution of methanol?
  • $$100\mathrm { mL }$$
  • $$112\mathrm { mL }$$
  • $$1000\mathrm { mL }$$
  • $$88\mathrm { mL }$$
Which of the following solution is hypertonic at constant identical temperature?
  • 1 M Aqueous glucose
  • 1 M Benzoic acid in benzene
  • 1 M aqueous ammonium phosphate
  • 1 M aqueous calcium chloride
The equilibrium constant for the following equilibrium is given at $$0^0C$$:

$$Na_2HPO_4.12H_2O(s)\rightarrow Na_2HPO_4.7H_2O(s)+5H_2O(g); K_p=31.25 \times 10^{-13}$$. 

The vapor pressure of water is:
  • $$2 \times 10^{-4}\,atm$$
  • $$5 \times 10^{-4}\,atm$$
  • $$5 \times 10^{-2}\,atm$$
  • $$5 \times 10^{-3}\,atm$$
The relative lowering of vapour pressure of a solution of $$6g$$ of urea in $$90g$$ of water is equal to.
  • $$0.02$$
  • $$0.04$$
  • $$0.60$$
  • $$0.03$$
When metal 'M' is treated with $$NaOH$$, a white gelatinous precipitate 'X' is obtained, which is soluble in excess of $$NaOH$$. Compound 'X' when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal 'M' is:
  • $$Ca$$
  • $$Al$$
  • $$Fe$$
  • $$Zn$$
A chemist decided to determine the molecular formula of an unknown compound. He collects following information's:
(I) Compounds contain $$2:1$$ 'H' to 'O' atoms(number of atoms).
(II) Compounds has $$40\%$$ C by mass
(III) Approximate molecular mass of the compound is $$176$$g
(IV) Compound contains C, H and O only.
What is the $$\%$$ by mass of oxygen in the compound?
  • $$53.33\%$$
  • $$88.88\%$$
  • $$33.33\%$$
  • None of these
If a solute A dimerizes in water at 1atm pressure and the boiling point of the solution is 100.52$$^o$$C. If 2 moles of A is added to 1 kg of water and $$K_b$$ for water is 0.52$$^o$$C/molal, calculate the percentage association of A.
  • 50
  • 30
  • 25
  • 100
For a very dilute solution of $$H_3PO_3$$ van't Hoff factor is.
  • $$i = 7$$
  • $$i = 3$$
  • $$i = 4$$
  • $$i = 5$$
Acetic acid exists in benzene solution in dimer form. In an actual experiment, the van't Hoff factor was found to be $$0.52$$. Then the degree of association of acetic acid is.
  • $$0.48$$
  • $$0.88$$
  • $$0.96$$
  • $$0.52$$
A sphere of diameter 7 cm and mass 266.5 g floats in a both of liquid. As the temperature is raised, the sphere just sinks at a temperature of 35 C. If the density of the liquid at 0 C is $$1.527 g cm^{-3}$$, then the coefficient of a cubical expansion of the liquid is 
  • 0.0043/C
  • 0.00083/C
  • 0.00025/C
  • 0.00010/C
50L of a certain liquid is confined in a piston system at the external pressure 100 atm. This pressure is suddenly released and liquid is expanded against the constant one atmosphere pressure, volume of the liquid increases by 1L and the final pressure on the liquid is 10 atm. Find the magnitude of work done.
  • $$1\ L\ atm$$
  • $$5\ L\ atm$$
  • $$50\ L\ atm$$
  • $$500\ L\ atm$$
Which of the following has maximum van't Hoff factor?
  • 90% ionized $$K_{2}SO_{4}$$
  • 60% ionized $$NaCI$$
  • 50% ionized $$K_{4}[Fe(CN)_{6}]$$
  • 100% ionized $$KOH$$
$$18\ g$$ of glucose is dissolved in $$90\ g$$ of water. The relative lowering of vapour pressure of solution is 
  • $$\dfrac{1}{51}$$
  • $$\dfrac{1}{5.1}$$
  • $$\dfrac{18}{108}$$
  • $$\dfrac{50}{51}$$
For the equilibrium, $$CH_3-CH_2-CH_2-CH_3(g)\leftrightharpoons CH_3-CH(CH_3)-CH_3(g)$$
                                                                                                 isobutane
If the value of $$ K_c$$ is $$3.0, $$ the percentage by mass of iso-butane in the equilibrium mixture would be :
  • 75 %
  • 90 %
  • 30 %
  • 60 %
At $${40^ \circ }C$$ the vapour pressure ( in torr ) of a mixture of methyl alcohol and ethyl alcohol is represented by $$P = 199x + 135$$
(where $$x$$ is the mole fraction of methyl alcohol) 
What are the vapour pressures of pure methyl alcohol and pure ethyl alcohol at $${40^ \circ }C$$ ?
  • $$135$$ and $$254$$ torr
  • $$119$$ and $$135$$ tor
  • $$119$$ and $$254$$ torr
  • $$334$$ and $$135$$ torr
The vapour pressure of a solvent decreases by $$10\ mmHg$$ when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.If the decrease in vapour pressure is $$20\ mmHg$$ then the mole fraction of the solvent is:
  • $$0.8$$
  • $$0.6$$
  • $$0.4$$
  • None
$$6\ g\ urea$$ is dissolved in $$90\ g\ water$$. The relative lowering of vapour pressure is equal to:
  • $$0.0196$$
  • $$0.06$$
  • $$1.10$$
  • $$0.0202$$
A mixture of 50.ml of $$N{H_3}$$ and 60.0 ml of $${O_2}$$ gas react as
$$4N{H_3}(g) + 5{O_2}(g)\xrightarrow{{}}4NO + 6{H_2}O(g)$$
If all the gases are at the same temperature and the reaction continues until one of the gases is completely consumed, what volume of water vapour is produced?
  • 48 mL
  • 60.0mL
  • 72 mL
  • 75.0 mL
The Vant Hoff factor (i) for a dilute solution of $$K_3[Fe(CN)_6]$$ is (Asuming $$100\%$$ ionsation):
  • 10
  • 4
  • 5
  • 0.25
Calculate the mass of a non - volatile solute (molar  mass $$40\,\,g mol^{-1}$$) which should be dissolved in $$114g$$ octane to reduce its vapour pressure to $$80\%$$
  • $$2g$$
  • $$4g$$
  • $$8g$$
  • $$10g$$
What is the Van't Hoff factor of 50% ionized $$K_{2}SO_{4}$$ ?
  • 1
  • 1.5
  • 2
  • 2.5
Consider the followimg Vapour Pressure - Mole fraction graph. SP (Total vapour pressure of the resultant solution) is equal to
1301464_35fd1e25e047480a9b506d47311a4ba6.png
  • PQ+RS
  • PQ+QR+RS
  • SR+SQ
  • PQ+QR
For which solution the value of Van't hoff factor is not equal to 1?
  • Glucose
  • Sugar
  • Fructose
  • Acetic acid
The vapour pressure of two volatile liquid mixtures is $$P_T =5.3+2X_B$$ (in mm of Hg), where $$X_B$$ is mole fraction of B in mixture. What is the ratio of mole fractions of A & B in liquid phase.
( $$P_A \ and\  P_B$$ are vapour pressures of A & B) 
  • $$\dfrac { 73 }{ 53 }$$
  • $$\dfrac { 73 }{ 53 } \times \dfrac { P_{ A } }{ { P }_{ B } }$$
  • $$\dfrac { 53 }{ 73 }$$
  • $$\dfrac { 53 }{ 73 } \times \dfrac { P_{ A } }{ { P }_{ B } }$$
Which of the following has maximum Van't hoff 's factor?
  • 90% ionized $$K_{2}SO_{4}$$
  • 60% ionized $$NaCl$$
  • 50% ionized $$K_{4}[Fe(CN)_{6}]$$
  • 100% ionized $$KOH$$
Calculate the vapour pressure of aqueous 0.1 m glucose solution at 300 K temperature, the vapour pressure of water is 0.03 bar at 300 K temperature.
  • 0.5 bar
  • 0.29 bar
  • 0.3 bar
  • 0.03 bar
An ideal solution contains two volatile liquid A $$(p^{0}$$=100 torr) and B $$\ (P^{0}$$=200 torr). If the liquid mixture contains 1 mole of A and 4 mole of B then the total vapour pressure of the mixture obtained by condensing the vapour above this solution in a beaker is
  • 180 torr
  • 188.8 torr
  • 175 torr
  • 198.8 torr
$$5.0\ L$$ water placed in a closed room of volume $$2.5\times 10^{4}L$$ having temperature $$300\ K$$. If vapour pressure of water is $$27.0\ mm$$ and density is $$0.990\ g/cm^{3}$$ at this temperature, how much water is left in liquid state?  
  • $$3.444\ L$$
  • $$4.344\ L$$
  • $$4.798\ L$$
  • $$1.212\ L$$
Two liquids A and B have $${P_A}^0:{P_B}^0$$ = 1:3 at a certain temperature. If the mole fraction ratio  $${x_A}:{x_B} = $$ 1:3, the mole fraction of A in vapour in equilibrium with the solution at the given temperature is -        
  • 0.1
  • 0.2
  • 0.5
  • 1.0
When $$80 mL$$ of $$0.20 M$$ $$HCl$$ is mixed with $$120 mL$$ of $$0.15 M$$ $$KOH$$, the resultant solution is the same as a solution of:
  • $$0.16 M$$ $$KCl$$ and $$0.02 M$$ $$HCl$$
  • $$0.08 M$$ $$KCI$$
  • $$0.08 M$$ $$KCl$$ and $$0.01 M$$ $$KOH$$
  • $$0.08 M$$ $$KCl$$ and $$0.01 M$$ $$HCI$$
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