Boiling and Freezing Points of Solutions, Class 12 Chemistry NCERT Solutions

1. There will be total 20 MCQ in this test.
2. Please keep a pen and paper ready for rough work but keep your books away.
3. The test will consist of only objective type multiple choice questions requiring students to mouse-click their correct choice of the options against the related question number.
4. No negative marking for incorrect choice.
5. Please click on “Finish the Test” when you want to exit.
6. All the best – Happy Studying

1. If 2 moles of sugar are dissolved in 1000g of water, the elevation in boiling point of the resulting solution is: (Kb = 0.52 K kg mol^-1):

1.04°C

100 °C

0.52° C

101.04K

Your comments:

Question 1 of 20

2. The molal elevation constant is the elevation in boiling point of

1M solution

1m solution

1N solution

None of the above

Your comments:

Question 2 of 20

3. The colligative properties of a solution are

Proportional to the number of solute particles present

Proportional to percentage of solute

Proportional to normality of solution

Proportional to volume of solution

Your comments:

Question 3 of 20

4. The information that is/are needed to determine the molar mass of an unknown solute is/are

The amount of solute used in the experiment

The molal boiling or freezing constant value of the solvent

The amount of solvent used in the experiment

All the above

Your comments:

Question 4 of 20

5. What is the boiling point of a 3 molal aqueous solution if Kb is 0.512°C/m?

101 K

101.536 °C

90.536 °C

0 K

Your comments:

Question 5 of 20

6. Which of the following is a colligative property?

Molality

Viscosity

Relative lowering of vapour pressure

Surface tension

Your comments:

Question 6 of 20

7. Beckmann thermometers are used to measure

boiling point of solution

elevation in boiling point or depression in freezing point

any temperature

freezing point of solution

Your comments:

Question 7 of 20

8. What is the symbol for cryoscopic constant?

Ffb_fb

K_fb

K_f

K_b

Your comments:

Question 8 of 20

9. Which formula correctly represents the relative lowering of vapour pressure?

A

B

C

D

Your comments:

Question 9 of 20

10. A solution was made by dissolving 2 g of a solute in 100 g of acetone. The solution boiled at 56.95° C. The boiling point of pure acetone is 55.95° C, and the Kb =1.71°C/m. What is the molecular weight of the solute?

22 g

34.2 g

42.3 g

30 g

Your comments:

Question 10 of 20

11. The molal elevation constant is the ratio of the elevation in B.P to:

Molality

Mole Fraction of solute

Molarity

Mole fraction of solvent

Your comments:

Question 11 of 20

12. Which of the two has lower freezing point, 2m NaCl or 5m NaCl aqueous solution?

2m NaCl solution

Both have same freezing point

5m NaCl solution

The solutions cannot freeze

Your comments:

Question 12 of 20

13. If the vapour pressure of pure solvent A is 17.5 mm and lowering of vapour pressure of solution formed by adding a non-volatile electrolyte is 0.0175 mm then what is the relative lowering of vapour pressure?

0.1

1.01

0.001

0.01

Your comments:

Question 13 of 20

14. Solvent X boils at 78.5 °C and at 82.3 °C when nonvolatile solute Y is added to it. What is T_b?

3.8 °C

21 °C

–3.8 °C

16 °C

Your comments:

Question 14 of 20

15. Which of the following aqueous solution do you expect to have the lowest freezing point?

0.1 m NH₄Cl

0.1 m BaCl₂

0.1 m Al₂(SO₄)₃

0.1 m AlCl₃

Your comments:

Question 15 of 20

16. The freezing point of a 0.05 molal solution of a non electrolyte in water is (Kf = 1.86 k kg mol^-1)

-0.093 °C

-1.86 °C

0.93 °C

-0.93 °C

Your comments:

Question 16 of 20

17. 4g of two non volatile solutes A and B are separately dissolved in 100g of a given solvent. Which of the two shows higher elevation in boiling point if molar mass of A is more than that of B?

Boiling point remains unchanged

Both have same elevation in B.P.

Solution containing A

Solution containing B

Your comments:

Question 17 of 20

18. Relative lowering of vapour pressure is directly proportional to

Density of solution

Mole fraction of solute

Mass of solvent

Color of solution

Your comments:

Question 18 of 20

19. When common salt is dissolved in water:

Melting point of solution increases

Boiling point of solution increases

Boiling point of solution decreases

both melting .point and boiling point decreases

Your comments:

Question 19 of 20

20. Camphor is used as solvent to determine the molecular mass of non-volatile solute by Rast method because for camphor

molar depression constant is high

melting point is high

being cheap

all the above

Your comments:

Question 20 of 20

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