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NCERT Exemplar Solutions for Class 12 Chemistry Chapter 2 – Solutions are crucial for helping students grasp the fundamental concepts of this chapter. These solutions enable a thorough understanding, assisting students in achieving high marks in both the Class 12 board exams and graduate entrance examinations.
The NCERT Exemplar for Class 12 Chemistry Chapter 2 PDF is an essential study material that offers comprehensive solutions for the questions presented in the NCERT Exemplar book. In addition to NCERT questions, this PDF includes several extra questions curated by subject experts at Infinity Learn.
The solutions cover various types of questions such as MCQs, fill in the blanks, match the following, exercises, assignments, and numerical problems, all designed to enhance board exam preparation.
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Q. Mole fraction of glycerine C3H5(OH)3 in a solution containing 36 g of water and 46 g of glycerine is:
(a) 0.46
(b) 0.40
(c) 0.20
(d) 0.36
Answer: (c) 0.20
Q. Out of molality (m), molarity (M), formality (F), and mole fraction (x), those which are independent of temperature are:
(a) M, m
(b) F, x
(c) m, x
(d) M, x
Q. Answer: (c) m, x
Which of the following condition is not satisfied by an ideal solution?
(a) ΔHmixing=0
(b) ΔVmixing=0
(c) Raoult’s Law is obeyed
(d) Formation of an azeotropic mixture
Answer: (d) Formation of an azeotropic mixture
Q. The boiling point of an azeotropic mixture of water and ethanol is less than that of water and ethanol. The mixture shows:
(a) No deviation from Raoult’s Law
(b) Positive deviation from Raoult’s Law
(c) Negative deviation from Raoult’s Law
(d) The solution is unsaturated
Answer: (b) Positive deviation from Raoult’s Law
Also Read: NCERT Syllabus
Q. Which has the lowest boiling point at 1 atm pressure?
(a) 0.1 M KCl
(b) 0.1 M Urea
(c) 0.1 M CaCl2_22
(d) 0.1 M AlCl3_33
Answer: (b) 0.1 M Urea
Q. Osmotic pressure of a solution is 0.0821 atm at a temperature of 300 K. The concentration in moles/litre will be:
(a) 0.33
(b) 0.666
(c) 0.3 × 10−2
(d) 3
Answer: (c) 0.3 × 10−22
Q. People add sodium chloride to water while boiling eggs. This is to:
(a) Decrease the boiling point
(b) Increase the boiling point
(c) Prevent the breaking of eggs
(d) Make eggs tasty
Answer: (b) Increase the boiling point
Q. The van’t Hoff factor (i) accounts for:
(a) Degree of solubilisation of solute
(b) The extent of dissociation of solute
(c) The extent of dissolution of solute
(d) The degree of decomposition of solution
Answer: (b) The extent of dissociation of solute
Q. The molal elevation constant depends upon:
(a) Nature of solute
(b) Nature of the solvent
(c) Vapour pressure of the solution
(d) Enthalpy change
Answer: (b) Nature of the solvent
Q. The molal freezing point constant for water is 1.86° C/m. The freezing point of 0.1 m NaCl solution is expected to be:
(a) 13.6° C
(b) 68° C
(c) 34° C
(d) 136° C
Answer: (c) 34° C
Q. The solution containing 6.8 g of non-ionic solute in 100 g of water was found to freeze at -0.93°C. If Kf for water is 1.86, the molar mass of solute is:
(a) 13.6
(b) 68
(c) 34
(d) 136
Answer: (d) 136
Q. In case of electrolyte which dissociates in solution the Van’t Hoff factor, i is:
(a) > 1
(b) < 1
(c) = 1
(d) = 0
Answer: (a) > 1
Q. Which of the following salts will have the same value of Van’t Hoff’s factor (i) as that of K4[Fe(CN)6]?
(a) Al2(SO4)3
(b) NaCl
(c) Al(NO3)3
(d) Na2SO4
Answer: (a) Al2(SO4)3
Read More: NCERT Syllabus Class 12
Short Answer Types
Q. Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.
Ans. A solution is a homogeneous mixture of two or more chemically non-reacting substances. Types of solutions include gaseous, liquid, and solid solutions. Examples: air (gas in gas), saltwater (solid in liquid), and alloys (solid in solid).
Q. What is Raoult’s Law? How is it applied to solutions of non-volatile solutes?
Ans. Raoult’s Law states that the partial vapor pressure of each component in a solution is directly proportional to its mole fraction. For non-volatile solutes, the vapor pressure of the solution is equal to the vapor pressure of the solvent multiplied by the mole fraction of the solvent.
Q. Explain the term osmotic pressure and its importance in determining molar masses of solutes.
Ans. Osmotic pressure is the minimum pressure needed to prevent the flow of solvent into a solution through a semipermeable membrane. It is important for determining molar masses as it can be measured at room temperature and uses molarity instead of molality.
Q. Differentiate between molarity and molality. Why is molality preferred over molarity in certain cases?
Ans. Molarity is the number of moles of solute per liter of solution, while molality is the number of moles of solute per kilogram of solvent. Molality is preferred as it is independent of temperature changes, unlike molarity which varies with temperature.
Q. What is Henry’s Law and mention its two important applications?
Ans. Henry’s Law states that the partial pressure of a gas in a liquid is directly proportional to the mole fraction of the gas. Applications include calculating the solubility of gases in liquids and designing pressurized containers.
Q. Define the terms ‘mole fraction’, ‘isotonic solutions’, ‘van’t Hoff factor’, and ‘ideal solution’.
Ans. Mole fraction: ratio of moles of one component to total moles in the mixture. Isotonic solutions: solutions with the same osmotic pressure. van’t Hoff factor: ratio of observed colligative property to that calculated for a non-electrolyte. Ideal solution: obeys Raoult’s Law under all conditions.
Q. What is meant by ‘colligative properties’? Give examples.
Ans. Colligative properties depend on the number of solute particles and not their nature. Examples include boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure.
Q. How is the depression in freezing point of a solution related to the molality of the solution?
Ans. Depression in freezing point is directly proportional to the molality of the solution. The relationship is given by ΔTf = Kf × m, where ΔTf is the depression in freezing point, Kf is the cryoscopic constant, and m is the molality.
Q. Calculate the molarity of a 68% (by mass) nitric acid solution with a density of 1.504 g/mL.
Ans. For a 68% solution, 68 g of HNO3 is present in 100 g of solution. Using the density, the volume of the solution can be calculated, and then molarity (moles of solute per liter of solution) can be determined.
Q. Why do non-ideal solutions exhibit deviations from Raoult’s Law? Provide examples of positive and negative deviations.
Ans. Non-ideal solutions exhibit deviations due to differences in intermolecular interactions. Positive deviations occur when A-B interactions are weaker than A-A or B-B (e.g., ethanol and acetone). Negative deviations occur when A-B interactions are stronger (e.g., chloroform and acetone).
Q. Explain why aquatic species are more comfortable in cold water rather than in warm water.
Ans. Cold water holds more dissolved oxygen than warm water, providing a better environment for aquatic species.
Q. What is the van’t Hoff factor for KCl and K2SO4? Explain its significance.
The van’t Hoff factor for KCl is 2 and for K2SO4 is 3. It indicates the number of particles into which a solute dissociates in solution, affecting colligative properties.
Q. What is reverse osmosis? How does it differ from regular osmosis?
Ans. Reverse osmosis is the process where solvent molecules move from a region of higher solute concentration to lower concentration through a semipermeable membrane by applying pressure, opposite to the direction of natural osmosis.
Q. Describe the concept of vapor pressure lowering. Why is it considered a colligative property?
Ans. Vapor pressure lowering occurs when a non-volatile solute is added to a solvent, decreasing the solvent’s vapor pressure. It is considered a colligative property because it depends on the number of solute particles, not their identity.
Q. What are azeotropes? Give examples of minimum and maximum boiling azeotropes.
Ans. Azeotropes are mixtures with a constant boiling point. Minimum boiling azeotropes (e.g., ethanol-water) show positive deviation from Raoult’s Law, while maximum boiling azeotropes (e.g., hydrochloric acid-water) show negative deviation.
More Resources for Class 12
- NCERT Exemplar Solutions for Class 12 Physics
- NCERT Exemplar Solutions for Class 12 Biology
- NCERT Exemplar Solutions for Class 12 Maths
FAQs on NCERT Exemplar Solutions for Class 12 Chemistry Chapter 2
What are the main topics covered in Chapter 2 of the NCERT Exemplar for Class 12 Chemistry?
Chapter 2 of the NCERT Exemplar for Class 12 Chemistry, titled Solutions, covers a range of topics including types of solutions, concentration of solutions, solubility, colligative properties, Raoult's Law, and the ideal and non-ideal solutions. These concepts are fundamental for understanding the behavior of solutions in various chemical processes. For detailed explanations and exemplar solutions, you can refer to resources provided by Infinity Learn.
How do NCERT Exemplar Solutions help in preparing for competitive exams like NEET and JEE?
NCERT Exemplar Solutions for Class 12 Chemistry provide comprehensive explanations and a variety of practice problems, including multiple-choice questions (MCQs) that are essential for competitive exams like NEET and JEE. These solutions help in reinforcing the concepts, improving problem-solving skills, and familiarizing students with the types of questions that may appear in these exams. For more focused practice, you can explore the materials available at Infinity Learn.
Where can I find the NCERT Exemplar Solutions for Class 12 Chemistry Chapter 2 in a downloadable PDF format?
You can find the NCERT Exemplar Solutions for Class 12 Chemistry Chapter 2 in a downloadable PDF format from various educational websites, including Infinity Learn. These PDFs provide step-by-step solutions to exemplar problems, helping students to thoroughly understand the concepts and prepare effectively for their board exams and competitive entrance tests.
