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

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

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

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

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

Question 5 of 20

6. Which of the following is a colligative property?

 Molality

  Viscosity

 Relative lowering of vapour pressure

  Surface tension

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

Question 7 of 20

8. What is the symbol for cryoscopic constant?

  Ffb_fb

 K_fb

 K_f

 K_b

Question 8 of 20

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

 A

 B

 C

 D

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

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

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

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

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

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

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

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

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

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

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

Question 20 of 20

 Loading…