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CPU 4 - Colligative Properties II (Depression In Freezing Point) - Class 12 MCQ


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20 Questions MCQ Test - CPU 4 - Colligative Properties II (Depression In Freezing Point)

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CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 1

Only One Option Correct Type
This section contains 11 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct


Q.

Addition of 0.643 g of a compound to 50 mL of benzene (density = 0.879 g mL-1) lowers the freezing point from 5.51°C to 5.03°C

(Kf of benzene = 5.12 K mol-1 kg). Molar mass of the compound is 

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 1

On adding   mole of solute to w2 g of solvent, depression in freezing point is

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 2

The coolant usually contains a solution of antifreeze prepared by mixing equal volumes of ethylene glycol C2H4(OH)2 and water. The density of ethylene glycol is 1.113 g cm-3. Thus, the freezing point of the mixture is

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 2

(a) S o lu te is e th y le ne g ly c o l = 1 m L = 1.113 g (w1

∴  Freezing point = 0 - 33.39° = - 33.390

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CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 3

A 5% solution (by mass) of cane sugar in water has freezing point of 272.88 K. Thus, freezing point of 5% glucose in water is (freezing point of pure water is 273.15 K) 

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 3

(a) ΔT, (cane sugar) = 273.15 - 272.88= 0.27o 

ΔT, (glucose) = ?

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 4

30 mL of CH3OH (d = 0.7980 g cm-3) and 70 mL of H2O(of = 0.9984 g cm-3) are mixed at 25° C to form a solution of density 0.9575 g cm-3. Thus, depression in freezing point is (Kf for H20 =1.86 K mol-1 kg)

 

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 4

 

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 5

How much ethyl alcohol (C2H5OH) must be added to 1 L of water so that solution will not freeze at - 4 ° F? (Kf of H20 = 1.86° m ol-1 kg)

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 5

(d) -4°F is to be converted into°C

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 6

CH3OH is 10% by weight of solution of CH3OH in water (Kf of H20 = 1.86° mol-1 kg). Thus, freezing point of the solution is 

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 6

(a) CH3OH solution is 10 % by weight of solution.
Thus, 100 g solution has CH3OH = 10g

Water in solution = 100 - 10 = 90 g

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 7

The amount of ice that will separate out on cooling a solution containing 50 g of ethylene glycol in 200 g w ater to -9.3° C is (Kf of H20 = 1.86° mol-1 kg)

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 7

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 8

A solution of a non-volatile solute in water freezes at - 0.30° C. The vapour pressure o f pure w ater at 298 K is 23.51 torr. For water, Kf = 1.86 K mol-1 kg. Thus, vapour pressure of the solution (in torr)

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 8

(a) For    mole of non-volatile solute in w2 g solvent, depression in freezing point is

By Raoult’s law,

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 9

 

A solution is prepared by condensing 4 L o f a gas measured at 27° C and Working Space 748 mm Hg pressure into 58 g benzene (Kf of benzene = 5.12 K mol-1 kg). Thus, depression in freezing point is

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 9

w1/m1 moles of solute has not been given, but this amount has been obtained by condensation into benzene.

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 10

What freezing point depression would be predicted for 0.1 molal solution of benzoic acid in benzene if latent heat of fusion is 30.00 cal g-1 at 280 K (freezing point) for benzene? (assume no change in molecular state)

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 10

(a) ΔT0 = Freezing point of solvent

ΔHf - Latent heat of fusion

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 11

Based on the given graph, molar mass of solute X (non-electrolyte) is

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 11

(a)

From the given graph , at  point A

Liquid solvent Solid solvent

Thus, freezing point of solvent = 279 K Freezing point of 1 molal solution of Xat point B = 273 K Thus, AT, =279 - 273 = 6 K 

Also, ΔTf = Kf x molality = Kf x 1

Kf = 6 K mol-1 kg

For 10% solution of X in solvent,

w1 = 10 g, w2 =100 g

m1 = molar mass of solute X

At point C , freezing point of 10% solution = 268 K

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 12

Statement Type
This section is based on Statement I and Statement II. Select the correct anser from the codes given below

Q.

Statement I : Freezing point of a solution is smaller than that of the solvent.

Statement II At freezing point, solid and liquid exist in equilibrium and T(fp) = 

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 12

 (b)

When a non -volatile solute is added to a solvent, temperature falls, hence vapour pressure also falls . Thus , freezing point is also lowered.

At A, vapour pressure = p0

freezing point=T0

At B,vapour pressure=p< p0

and freezing point = T1<T

Thus, freezing point is lowered. Hence,StatementIiscorrect.
At freezing point,

ΔH is almost same for solvent and solution but entropy increases, ΔS>0. Hence, freezing point of solution is smaller than that of solvent.
Thus, Statement II is correct but not the correct explanation of Statement I.

*Multiple options can be correct
CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 13

One or More than One Options Correct Type
This section contains 2 multiple type questions. Each question has 4 choices (a), (b), (c) and (d), out of which ONE or MORE THAN ONE are correct.

Q.

In the depression of freezing point experiment, it is found that the

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 13

(a, d) Liquid solvent   Solid solvent

Freezing point is the temperature at which liquid solvent and solid remain at equilibrium . In the following figure ,

On adding solute to solvent, vapour pressure falls p1 < p0 and T1<T0

Thus, (a) is correct.
Only solvent molecules solidify at the freezing point.
Thus, (d) is also correct.

*Multiple options can be correct
CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 14

A solution containing 3.5 g of solute X is 50.0 g of water has a volume of 52.5 mL and a freezing point of - 0.86° C. Thus, (Kf of H20 = 1.86° mol-1 kg)

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 14

(b) Total mass of solution = 50 .0 + 3.5 Volume of solution = 52 .5 m L

(c) 70 g X = 0 .4 6 mol (present in 1000 g H20 )

 

*Multiple options can be correct
CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 15

Matching List Type
Choices for the correct combination of elements from Column I and Column II are given as options (a), (b), (c) and (d), out of which one is correct

Q. 

Given, Kf of H20 =1.86° mol-1kg.
Match the solutions given in Column I with their depression in freezing points given in Column II and select the answer from the codes given below.

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 15

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 16

Comprehension Type
This section contains a passage describing theory, experiments, data, etc. Two questions related to the paragraph have been given. Each question has only one correct answer out of the given 4 options (a), (b), (c) and (d)

Passage

1 kg of 1 molal aqueous solution of sucrose is cooled and maintained at - 3.534° C. Kf (H20) = 1.86 K mol-1kg

Q.

 Relative lowering of vapour pressure 

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 16

Molality = 1 mol kg-1, Solute (sucrose ) =1 mole Solvent (H20 ) =1 kg = 1000 g = 55.55 moles

By Raou lt’s law for binary mixture of non -volatile solute in volatile solvent, relative lowering of vapour pressure = Xsoiute

S ucrose solution is maintained at -3 .534 °C .
Thus, ΔTf = 3.534°C

Total mass of 1 molal solution = 1000 g (solvent) + 342 g (solute) = 1342 g

1342 g solution contains sucrose = 342 g

1000 g solution contains sucrose = 

H20 present in 1000 g solution = 1000 - 255 = 745 g

Solvent actually required to keep 255g sucrose in solution at -3 .534°C = w2

Thus , ice form ed = 745 - 392 = 353 g (in solid state ) 

CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 17

Passage

1 kg of 1 molal aqueous solution of sucrose is cooled and maintained at - 3.534° C. Kf (H20) = 1.86 K mol-1 kg

Q.

How much ice will separate under the given conditions?

Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 17

 

Molality = 1 mol kg-1, Solute (sucrose ) =1 mole Solvent (H20 ) =1 kg = 1000 g = 55.55 moles

By Raou lt’s law for binary mixture of non -volatile solute in volatile solvent, relative lowering of vapour pressure = Xsoiute

S ucrose solution is maintained at -3 .534 °C .
Thus, ΔTf = 3.534°C

Total mass of 1 molal solution = 1000 g (solvent) + 342 g (solute) = 1342 g

1342 g solution contains sucrose = 342 g

1000 g solution contains sucrose = 

H20 present in 1000 g solution = 1000 - 255 = 745 g

Solvent actually required to keep 255g sucrose in solution at -3 .534°C = w2

Thus , ice form ed = 745 - 392 = 353 g (in solid state ) 

*Answer can only contain numeric values
CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 18

One Integer Value Correct Type
This section contains 3 questions, when worked out will result in an integer value from 0 to 9 (both inclusive)

Q.

At 100° C and 1 atm, following equilibrium is set up

Volume occupied by water mole, in 10 L steam is x cm3. What is the value of x?


Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 18

6) Density of water vapour = 6 x10-4 g cm3 

Thus, weight of water vapour in 10 L steam =10 x1000 x 6 x10-4 = 6g

Density of liquid water = 1 g cm3 

Volume of liquid water in 6 g steam = 

*Answer can only contain numeric values
CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 19

Molecular formula of white phosphorus in benzene is (P)x. What is the value of x based on following experiment?

Freezing point of benzene = 5.45° C Kf (benzene) = 5.12 K mol-1 kg

Freezing point of solution containing 0.675 g of white phosphorus in 50.0 g of benzene = 4.89° C.


Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 19

w1/ m1 = moles of solute, w2 = mass of solvent

 

If molecular formula = (P)x

Molar mass = 31x = 123.42

x = 4

*Answer can only contain numeric values
CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 20

One molal aqueous solution of urea freezes at -1.86° C. Aqueous solution of CnH2nOn  36% by mass of water freezes at -3.72° C. What is the value of n?


Detailed Solution for CPU 4 - Colligative Properties II (Depression In Freezing Point) - Question 20

(6) Molality of urea solution = 1 mol kg-1

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