PARIKSHA SUTRA

Home › Practice › Class 12 › Chemistry

Solutions MCQs

Class 12 Chemistry — questions with answers and worked explanations.

20 free questions Class 12 Chemistry Answers + explanations No sign-up

These questions are drawn from the Pariksha Sutra question bank for Solutions, part of the Class 12 Chemistry syllabus. Each one shows the correct answer and, where a method helps, the working behind it.

Read the question, decide your answer before looking, then check the explanation — that is what turns practice into marks. If a question catches you out, the explanation is the part worth re-reading.

Questions

Question 1
Which of the following is an example of a solid solution in which both the solute and solvent are solids?
  1. Brass (Cu and Zn alloy)
  2. Camphor in nitrogen gas
  3. Amalgam of mercury with sodium
  4. Aerated water (CO2 in water)
Answer: Brass (Cu and Zn alloy)
Question 2
Calculate the mass percent of urea in a solution made by dissolving 10 g of urea in 90 g of water.
  1. 90%
  2. 11.1%
  3. 10%
  4. 9%
Answer: 10%
Question 3
Raoult's law states that the partial vapour pressure of a component in a solution is proportional to its:
  1. Mole fraction in solution
  2. Volume in solution
  3. Mass percent in solution
  4. Molarity in solution
Answer: Mole fraction in solution
Question 4
A mixture of acetone and chloroform shows negative deviation because:
  1. A-B interactions are weaker than pure components
  2. The mixing is highly endothermic
  3. Both are non-polar liquids
  4. Hydrogen bonding forms between chloroform H and acetone O
Answer: Hydrogen bonding forms between chloroform H and acetone O
Question 5
18 g of glucose (molar mass 180 g/mol) is dissolved in 1 kg of water (Kb = 0.52 K kg/mol). The elevation in boiling point is:
  1. 0.52 K
  2. 0.1 K
  3. 0.26 K
  4. 0.052 K
Answer: 0.052 K
Question 6
A sample of water contains 20 mg of dissolved salt in 1 kg of water. What is the concentration in ppm?
  1. 200 ppm
  2. 2 ppm
  3. 20 ppm
  4. 0.2 ppm
Answer: 20 ppm
Question 7
If the partial pressure of a gas over a solution is 2 bar and its Henry's law constant is 50 bar (mole fraction units), the mole fraction of the gas in solution is:
  1. 0.02
  2. 0.4
  3. 0.25
  4. 0.04
Answer: 0.04
Question 8
Which of the following pairs behaves most nearly as an ideal solution?
  1. n-hexane and n-heptane
  2. Water and nitric acid
  3. HCl and water
  4. Acetone and chloroform
Answer: n-hexane and n-heptane
Question 9
For a solution with molality 0.5 mol/kg and Kb = 0.52 K kg/mol, the elevation in boiling point is:
  1. 1.04 K
  2. 0.13 K
  3. 0.26 K
  4. 0.52 K
Answer: 0.26 K
Question 10
Two solutions having the same osmotic pressure at a given temperature are said to be:
  1. Isotonic
  2. Saturated
  3. Hypertonic
  4. Hypotonic
Answer: Isotonic
Question 11
A solution of oxygen dissolved in nitrogen gas is an example of which type of solution?
  1. Liquid in gas
  2. Gas in liquid
  3. Gas in gas
  4. Gas in solid
Answer: Gas in gas
Question 12
How many grams of glucose (molar mass 180 g/mol) are required to prepare 2 L of a 0.5 mol/L solution?
  1. 360 g
  2. 90 g
  3. 45 g
  4. 180 g
Answer: 180 g
Question 13
For a solution of two volatile liquids A and B, the total vapour pressure is given by:
  1. pA0 xA + pB0 xB
  2. pA0 xA - pB0 xB
  3. pA0 + pB0
  4. pA0 xB + pB0 xA
Answer: pA0 xA + pB0 xB
Question 14
A maximum boiling azeotrope is formed at a specific composition by solutions showing:
  1. Negative deviation from Raoult's law
  2. Zero vapour pressure
  3. Ideal behaviour
  4. Positive deviation from Raoult's law
Answer: Negative deviation from Raoult's law
Question 15
Molal elevation constant Kb is also known as the:
  1. van't Hoff constant
  2. Cryoscopic constant
  3. Ebullioscopic constant
  4. Osmotic constant
Answer: Ebullioscopic constant
Question 16
Which of the following represents a solution of a solid solute in a liquid solvent?
  1. Sugar dissolved in water
  2. Ethanol dissolved in water
  3. Oxygen dissolved in water
  4. Chloroform mixed with nitrogen gas
Answer: Sugar dissolved in water
Question 17
Which of the following expresses concentration as moles of solute per kilogram of solvent?
  1. Mass percent
  2. Molality
  3. Mole fraction
  4. Molarity
Answer: Molality
Question 18
At 300 K, pure liquid A has vapour pressure 100 mm Hg and pure B has 60 mm Hg. If mole fractions are xA = 0.5 and xB = 0.5, the total vapour pressure of the ideal solution is:
  1. 80 mm Hg
  2. 160 mm Hg
  3. 60 mm Hg
  4. 100 mm Hg
Answer: 80 mm Hg
Question 19
Which of the following is NOT a colligative property?
  1. Depression of freezing point
  2. Osmotic pressure
  3. Elevation of boiling point
  4. Optical activity
Answer: Optical activity
Question 20
The molal depression constant (Kf) is also called the:
  1. Osmotic constant
  2. Henry's constant
  3. Cryoscopic constant
  4. Ebullioscopic constant
Answer: Cryoscopic constant

30 more questions on this chapter

The full chapter test is timed, gives an All-India rank and a subject-wise breakdown of where you lost marks.

See the test series →

Other chapters

Hydrocarbons Ray Optics and Optical Instruments Organic Chemistry – Some Basic Principles and Techniques Structure of Atom Chemical Thermodynamics Equilibrium Some Basic Concepts of Chemistry Electrochemistry Chemical Bonding and Molecular Structure Laws of Motion Chemical Kinetics Wave Optics Electrostatic Potential and Capacitance Current Electricity Moving Charges and Magnetism Aldehydes, Ketones and Carboxylic Acids Principles of Inheritance and Variation Human Health and Disease Biotechnology: Principles and Processes Coordination Compounds Molecular Basis of Inheritance Cell: The Unit of Life Integrals Trigonometric Functions Limits and Derivatives Complex Numbers and Quadratic Equations Sequences and Series Probability Mental Maths practice