12th CBSE Solution important question and Answers

12th CBSE Solution Important Questions and Answers

Boost your board exam preparation with Agastya Classes’ curated question bank on the CBSE Class 12 Chemistry Chapter: Solutions.

📘 Why This Chapter is Important

The chapter “Solutions” forms a critical part of the CBSE Class 12 Chemistry syllabus. It covers concepts such as molarity, molality, Raoult's Law, colligative properties, and vapor pressure — all of which are essential for both board exams and competitive exams like NEET & JEE.

✅ Benefits of Practicing Important Questions

• Improves conceptual clarity on topics like boiling point elevation, freezing point depression, and van’t Hoff factor.
• Enhances numerical solving speed and accuracy.
• Familiarizes students with CBSE board exam pattern.
• Builds confidence through repeated exposure to frequently asked questions.

🧠 Topics Covered in the Question Set

• Types of Solutions
• Concentration Terms – Molarity, Molality, Mass %
• Henry’s Law and Solubility
• Raoult’s Law and Ideal vs Non-Ideal Solutions
• Colligative Properties – Numerical Applications
• Azeotropes and Abnormal Molar Masses

Practice makes perfect! Solving these questions will prepare you thoroughly for your upcoming exams.

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❓ Frequently Asked Questions (FAQs)

Q1. Are these questions based on the latest CBSE syllabus?

✅ Yes, all questions are updated as per the latest CBSE 2024–25 syllabus and board exam pattern.

Q2. Are solutions provided with these questions?

✅ Absolutely! Each question is accompanied by its correct answer. For complex numericals, step-by-step solutions are available.

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🔗 Related Resources

• 10th CBSE Carbon and its compound previous year questions
• 12th HSC Halogen Derivatives Previous year questions
• Join Agastya Home & Online Tuition

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Class 12 CBSE  – Chapter: Solutions Question and Answers

📘 Combined Worksheet 

🔹 Section A: 1-Mark Questions (Objective / VSA)

Attempt all. Each carries 1 mark.

1. The rate at which a solid dissolves in liquid does not depend on:
   a. Concentration b. Particle size c. Temperature d. Pressure

2. The molal depression constant depends on:
   a. Vapour pressure b. Heat of solution c. Nature of solvent d. Nature of solute

3. Normality of 0.3 M phosphoric acid is:
   a. 0.6 b. 0.1 c. 0.9 d. 0.5

4. When blood cells are placed in pure water, they:
   a. Become white b. Shrink c. Diffuse d. Swell up

5. Which will form maximum boiling azeotrope?
   a. C₂H₅OH + H₂O b. None c. HNO₃ + H₂O d. C₆H₆ + C₆H₅CH₃

6. Which among the following shows negative deviation from Raoult’s law?
   a. Chloroform + benzene b. Acetone + benzene c. Methyl alcohol + water d. CCl₄ + chloroform

7. Which among the following shows positive deviation?
   a. Chloroform + benzene b. Acetone + aniline c. HCl + water d. Acetone + CS₂

8. The tanks used by divers are filled with air diluted with:
   a. Helium b. Argon c. Nitrogen d. Hydrogen

9. Volume of 0.1 M H₃PO₄ required to neutralize 40 mL of 0.1 M KOH is:
   a. 40 mL b. 20 mL c. 10 mL d. 60 mL

10. For an ideal solution, volume of mixing is:
    a. Increases b. Decreases c. Remains same d. None

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🔹 Section B: 2-Mark Questions (Short Answer)

Answer any 6. Each carries 2 marks.

Define the following:

11. a. Molality
    b. Molarity

12. What are azeotropes or constant boiling mixtures?

13. Why is osmotic pressure considered a colligative property?

14. Define:
    a. Cryoscopic constant
    b. Mass percentage

15. Name two ways to lower vapour pressure of a liquid.

16. Why is melting point used to check purity of a substance?

17. Why is ether not miscible in water?

18. Define the term osmotic pressure.

19. What type of mixtures distill at one temperature? Why?

🔹 Section C: 3-Mark Questions (Numerical Problems)

Answer any 4. Each carries 3 marks.

20. A solution contains 0.90 g of non-electrolyte in 87.90 g of benzene. Molecular mass is 103 g/mol. The boiling point rises by 2.6 K. Find molal elevation constant (Kb) of benzene.

21. Density of 85% phosphoric acid is given. Calculate the volume of solution containing 17 g of H₃PO₄.

22. A 0.1539 molal solution of cane sugar has freezing point 271 K. Calculate FP of solution with 5 g glucose in 100 g solution. (Kf = 1.86)

23. Find molality and molarity of 15% H₂SO₄ solution (density = 1.10 g/cm³; molar mass = 98 g/mol)

24. Calculate molality of a solution with 20.7 g K₂CO₃ in 500 mL of solution (density = 1 g/mL)

25. Calculate mass % of benzene (C₆H₆) and carbon tetrachloride (CCl₄) if 22 g of benzene is dissolved in 122 g of CCl₄.

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🔹 Section D: 4-Mark Conceptual + Numerical Question

26. a. Explain “colligative molality” with examples.

         b. Why do we get abnormal molecular masses using colligative properties?

27. The freezing point depression of 0.1 molal benzoic acid in benzene is 0.256 K. (Kf = 5.12 K·kg/mol) Calculate Van’t Hoff factor. What conclusion do you draw about molecular state of benzoic acid?

28. Two elements A and B form AB₂ and AB₄. 1 g of each in 20 g benzene lower freezing point by 2.3 K and 1.3 K. Kf = 5.1 K·kg/mol. Find atomic masses of A and B.

Q. No.	Answer	Q. No.	Answer
1	d	2	c
3	c	4	d
5	c	6	a
7	d	8	a
9	b	10	c
11	Definitions	12	Azeotropes
13	Depends on solute particles only	14	Definitions
15	Lower temp, add non-volatile solute	16	Impurities lower MP
17	No H-bonds	18	Pressure to stop osmosis
19	Azeotropes, constant boiling	20	2.514 K·kg/mol
21	Use density formula	22	268.92 K
23	1.8 m, 1.68 M	24	0.313 m
25	Benzene = 15.28%, CCl₄ = 84.72%	26	Theory of abnormal molar mass
27	Van’t Hoff factor < 1 ⇒ Association	28	A = 25.59 u, B = 42.64 u