1. Which of the following is a homogeneous mixture?
(a) Muddy water
(b) Milk in water
(c) Salt dissolved in water
(d) Chalk powder in water
2. The scattering of light by particles in a colloid is known as:
(a) Sublimation
(b) Tyndall effect
(c) Coagulation
(d) Centrifugation
3. A solution contains 10 g of solute dissolved in 90 g of solvent. Its mass by mass percentage is:
(a) 5%
(b) 10%
(c) 15%
(d) 20%
4. Which method is used to separate two immiscible liquids?
(a) Distillation
(b) Crystallization
(c) Separating funnel
(d) Paper chromatography
5. The process in which a solid changes directly into vapour on heating (below its melting point) is called:
(a) Evaporation
(b) Sublimation
(c) Distillation
(d) Deposition
6. Assertion (A): A solution of salt in water does not show the Tyndall effect.
Reason (R): Particles in a true solution are smaller than 1 nm and do not scatter light.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
7. Assertion (A): Solubility of most solid solutes in water increases with rise in temperature.
Reason (R): Solubility curves show that solubility of solids generally rises with temperature.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
8. Which of the following mixtures can be separated by paper chromatography?
(a) Common salt and water
(b) Different coloured components of black ink
(c) Oil and water
(d) Camphor and sand
9. In a 5% (m/v) glucose solution, the amount of glucose present in 200 mL of solution is:
(a) 5 g
(b) 10 g
(c) 15 g
(d) 20 g
10. Which of the following is an example of a colloid?
(a) Salt solution
(b) Milk
(c) Sand in water
(d) Copper sulphate solution
11. Define a saturated solution. Give one example from daily life.
12. Differentiate between evaporation and distillation (any two points).
13. What is the Tyndall effect? Name the type of mixture that shows this effect.
14. State two differences between a solution and a suspension.
15. Why is a separating funnel used to separate oil and water?
16. What is coagulation? Name one coagulant used in water purification.
17. Describe the steps involved in the laboratory preparation of pure crystals of copper sulphate from its impure sample.
18. A mixture contains ammonium chloride, common salt and sand. Describe how you would separate these components.
19. Explain with a labelled diagram how distillation can be used to separate a mixture of acetone and water.
20. Define the following terms with one example each: (i) dispersed phase (ii) dispersion medium (iii) emulsion.
21. Calculate the mass by volume percentage of a solution prepared by dissolving 8 g of sodium chloride in water to make 200 mL of solution. Show the formula and working.
22. (a) What are the three ways of expressing concentration of a solution? Give the mathematical formula for each.
(b) If 15 g of common salt is dissolved in 135 g of water, calculate the mass by mass percentage of the solution. Show full working.
23. Describe with a labelled diagram the process of paper chromatography. How is it used to separate the components of black ink? Explain the principle involved.
24. (a) Differentiate between a solution, a suspension and a colloid on the basis of particle size, visibility, settling and Tyndall effect.
(b) Explain how centrifugation and coagulation help in separating components of muddy water.
25. Read the passage and answer the questions that follow:
In coastal areas, salt is obtained from seawater by allowing it to evaporate in shallow pits. The water evaporates leaving behind salt crystals. This process is an example of separation of a homogeneous mixture.
(i) Name the method used for obtaining salt from seawater.
(ii) Why is the remaining liquid after partial evaporation called a saturated solution?
(iii) How is this method different from crystallization?
(iv) Name another homogeneous mixture from which a solid can be obtained by the same method.
26. Read the passage and answer the questions that follow:
A student mixed acetone and water in the laboratory. Acetone has a boiling point of 56 °C while water boils at 100 °C. The teacher suggested using a method that allows recovery of both liquids.
(i) Which separation technique will be used?
(ii) Why can this technique separate the two liquids?
(iii) Draw a labelled diagram of the apparatus used.
(iv) Name one everyday application where this technique is used.
1. (c) Salt dissolved in water — homogeneous mixture (solution).
2. (b) Tyndall effect.
3. (b) 10%.
4. (c) Separating funnel.
5. (b) Sublimation.
6. (a) Both true and R explains A.
7. (a) Both true and R explains A.
8. (b) Different coloured components of black ink.
9. (b) 10 g.
10. (b) Milk.
11. Maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature (1 mark). Example: saturated sugar solution (1 mark).
12. Evaporation: solvent is lost; no recovery of both components. Distillation: both components can be recovered; uses difference in boiling points (1+1).
13. Scattering of light by colloidal particles making the path visible (1 mark). Colloid (1 mark).
14. Solution: particles not visible, do not settle; Suspension: particles visible, settle on standing (1+1).
15. Oil and water are immiscible and form separate layers due to different densities (2 marks).
16. Process of clumping together of fine suspended particles by adding a substance (1 mark). Alum/fitkari (1 mark).
17. Prepare hot saturated solution → filter while hot → cool slowly without disturbing → filter crystals → wash and dry (any three steps with explanation, 1 mark each).
18. Sublimation for ammonium chloride (1 mark), dissolve residue in water and filter sand (1 mark), evaporate filtrate to get salt (1 mark).
19. Diagram with distillation flask, condenser, thermometer, conical flask (2 marks). Lower boiling liquid vaporises first and condenses (1 mark).
20. Dispersed phase: solute-like particles (1 mark); dispersion medium: component in which particles are suspended (1 mark); emulsion: liquid in liquid colloid, e.g., milk (1 mark).
21. % m/v = (mass of solute/volume of solution) × 100 = (8/200) × 100 = 4% (formula 1 mark, substitution 1 mark, answer 1 mark).
22. (a) % m/m, % m/v, % v/v with formulae (3 marks). (b) Total mass = 150 g; % m/m = (15/150) × 100 = 10% (working shown, 2 marks).
23. Diagram of paper chromatography setup (2 marks). Principle: different components move at different rates on paper due to differential adsorption (2 marks). Application to black ink (1 mark).
24. (a) Table comparison on four points (4 marks). (b) Centrifugation: heavier particles settle at bottom due to centrifugal force (½ mark); coagulation: alum causes particles to clump and settle (½ mark).
25. (i) Evaporation (1 mark). (ii) No more solute can dissolve at that temperature (1 mark). (iii) Crystallization involves slow cooling for pure crystals (1 mark). (iv) Sugar solution (1 mark).
26. (i) Distillation (1 mark). (ii) Boiling points differ by more than 25 °C (1 mark). (iii) Labelled diagram (1 mark). (iv) Obtaining distilled water or separation of petroleum products (1 mark).
All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.