Question Bank for 12th Class Chemistry Solutions / विलयन Case Based (MCQs) - Solutions

Direction (1 - 5): Read the following passage and answer the questions that follow.

The addition of non-volatile substances to a solvent decreases the vapour pressure and added solute particles affects the formation of pure solvent crystals. Decrease in freezing point is directly correlated to the concentration of solutes dissolved in the solvent. A soluble solid in solution has the effect of raising its boiling point.

(Reference: Jayawardena J, Vanniarachchi M, Wansapala M (2017). Freezing point depression of different sucrose solutions and coconut water. Journal of Food Science and Nutrition. 2. 68-71)

Assertion: When NaCI is added to water, a depression in freezing point is observed.

Reason: The lowering of vapour pressure of a solution causes depression in the freezing point

A)

Assertion and reason both are correct statements and reason is the correct explanation for assertion.

B)

Assertion and reason both are correct but reason is not the correct explanation for assertion.

C)

Assertion is correct but reason is wrong.

D)

Assertion is wrong but reason is correct.

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2)

Which of the following equimolar solution is expected to have the lowest freezing point?

A)

\[0\centerdot 5M\] \[{{H}_{2}}S{{O}_{4}}\]

B)

\[0\centerdot 5MHCl\]

C)

\[0\centerdot 5M\] \[A{{l}_{2}}{{\left( S{{O}_{4}} \right)}_{3}}\]

D)

\[0\centerdot 5M\] acetic acid.

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3)

What is the effect of the addition of sugar on the boiling and freezing points of water?

A)

Both boiling and freezing points increase

B)

Both boiling and freezing points decrease

C)

Boiling point decreases and freezing point increases.

D)

Boiling point increases and freezing point decreases.

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4)

The elevation in boiling point is directly proportional to

A)

mole fraction of the solution

B)

molarity of the solution

C)

molality of the solution

D)

molarity of the solvent.

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5)

The freezing point of 1 percent solution of lead nitrate in water will be

A)

below \[0{}^\circ C\]

B)

\[0{}^\circ C\]

C)

\[1{}^\circ C\]

D)

\[2{}^\circ C\]

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6)

Direction (6 - 10): Antifreeze prevents the freezing of water in the car radiator in subzero conditions. An antifreeze solution is prepared from 222.6 g of ethylene glycol and 200 g of water to be used by a family during their trip to Gulmarg.

The molality of the above antifreeze solution is

A)

\[1\centerdot 79m\]

B)

\[17\centerdot 1m\]

C)

\[17\centerdot 95m\]

D)

\[18\centerdot 55m\]

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7)

If the density of the above solution is \[1\centerdot 072g\,\,m{{L}^{-1}}\], then the molarity of the solution is

A)

\[9\centerdot 8M\]

B)

\[1\centerdot 9M\]

C)

\[9\centerdot 1M\]

D)

\[17\centerdot 95M\]

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8)

What amount of ethylene glycol is added to 1 L of water so as to prevent it from freezing at 258 K?

A)

\[0\centerdot 495g\]

B)

\[49\centerdot 5g\]

C)

\[4\centerdot 95g\]

D)

495 g.

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9)

If glycerol and methanol were sold at the same price in the market, which would be cheaper for preparing an antifreeze solution for the car radiator.

A)

Glycerol

B)

Methanol

C)

Both are equally cheap

D)

None of these.

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10)

Ethylene glycol is a

A)

monohydric alcohol

B)

dihydric alcohol

C)

trihydric alcohol

D)

benzyl alcohol.

View Solution

11)

Direction (11-15): The four colligative properties of the dilute solutions help in calculating the molecular mass of the solute which is often called observed molecular mass. It may be same as the theoretical molecular mass (calculated from the molecular formula) if the solute behaves normally in solution. In case, it undergoes association or dissociation, the observed molar mass gives different results. The nature of the solute in solution is expressed in terms of Van't Hoff factor (i) which may be 1 (if the solute behaves normally), less than 1 (if the solute associates) and more than 1 (if the solute dissociates). The extent of association or dissociation is represented by a which is :

\[\alpha =\frac{i-1}{\left( 1/n-1 \right)}\] or \[\frac{i-1}{n-1}\] (for association) (for dissociation)

The Van't Hoff factor for dilute solution of glucose is :

A)

zero

B)

1

C)

\[1\centerdot 5\]

D)

\[2\centerdot 0.\]

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12)

Which of the following is incorrect?

A)

Molecular mass of NaCI found by osmotic pressure measurements is half of the theoretical value

B)

Molecular mass of \[C{{H}_{3}}COOH\] in benzene found by cryoscopic method is double the theoretical value

C)

Osmotic pressure of \[1\centerdot 0M\] glucose solution is half of that of \[1\centerdot 0M\] NaCI solution.

D)

Molecular mass of HCI found by any colligative property will be same in aqueous solution and in benzene solution.

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13)

Benzoic acid undergoes demerisation in benzene solution. The Van't Hoff factor is related to degree of association '\[\alpha \]' of the acid as :

A)

\[i\,=1-\alpha \]

B)

\[i\,=1+\alpha \]

C)

\[i\,=1-\alpha /2\]

D)

\[i\,=1+\alpha /2\]

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14)

\[0\centerdot 1M\] \[{{K}_{4}}\left[ Fe{{\left( CN \right)}_{6}} \right]\] is 60% ionized. What will be Van't Hoff factor?

A)

\[1\centerdot 4\]

B)

\[2\centerdot 4\]

C)

\[3\centerdot 4\]

D)

\[4\centerdot 4\]

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15)

The molar mass of the solute sodium hydroxide obtained from the measurement of osmotic pressure of its aqueous solution at \[27\text{ }{}^\circ C\] is 25 g \[mo{{l}^{-1}}\]. Therefore, the percentage ionisation of solution is :

A)

75

B)

60

C)

80

D)

70

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16)

Direction (16 - 20): Osmosis plays a primary role in biological systems. Osmosis is a physicochemical process, in which the concentration difference between two solutions creates pressure difference (osmotic pressure) across a separating semipermeable membrane. Solvent transport takes place from the more diluted solution to that of higher concentration, until equilibrium is reached. Van't Hoff was the first to propose the formula for the osmotic pressure as Posm = CRT. For electrolyte solutions, Van't Hoff factor 'i' has to be taken into consideration. (Reference: Ivan L. Minkov, Emil D. Manev, Svetia V. Sazdanova and Kiril H. Kolikov. Equilibrium and Dynamic Osmotic Behaviour of Aqueous Solutions with Varied Concentration at Constant and Variable Volume; Hindawi, The Scientific World Journal, Volume 2013)

What will be the osmotic pressure in pascals exerted by dissolving 1 g of a polymer of molecular mass 185,000 g \[mo{{l}^{-1}}\] in 450 ml of solution at \[37\text{ }{}^\circ C\] ?

A)

\[30.57\times {{10}^{-5}}\]

B)

\[0\centerdot 0309\]

C)

\[29\centerdot 25Pa\]

D)

\[30\centerdot 9Pa.\]

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17)

What amount of \[CaC{{l}_{2}}\] (i = \[2\centerdot 5\], Mol. mass 111 g \[mo{{l}^{-1}}\]) is dissolved is \[2\centerdot 5L\] of water so that its osmotic pressure is \[0\centerdot 75atm\] at \[25\text{ }{}^\circ C\] ?

A)

\[3\centerdot 38g\]

B)

\[0\centerdot 33g\]

C)

3380 g

D)

\[33\centerdot 8g.\]

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18)

What is the osmotic pressure of a solution prepared by dissolving 25 mg of \[{{K}_{2}}S{{O}_{4}}\] (Mol. mass = 174 g \[mo{{l}^{-1}}\]) in 2 L of water at \[25\text{ }{}^\circ C\], assuming that it is completely dissociated.

A)

\[5\centerdot 38\times {{10}^{-3}}atm\]

B)

\[5\centerdot 27\times {{10}^{-3}}atm\]

C)

\[3\centerdot 37\times {{10}^{-3}}atm\]

D)

None of these.

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19)

Osmotic pressure can be increased by

A)

increasing temperature

B)

decreasing temperature

C)

increasing volume

D)

None of these.

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20)

Blood cells retain their normal shape in solution which are

A)

hypotonic to blood

B)

isotonic to blood

C)

hypenonic to blood

D)

equinormal to blood.

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12th Class Chemistry Solutions / विलयन Question Bank

done Case Based (MCQs) - Solutions Total Questions - 20

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Case Based (MCQs) - Solutions

Case Based (MCQs) - Solutions Total Questions - 20