Exploring Mixtures and their Separation - Chapter 5 Exploration

Q 1
Question
Which of the following mixtures are correctly classified as homogeneous (Hm) and heterogeneous (Ht)? Choose the correct option.
(i) Air — Hm, Milk — Ht, Sugar solution — Hm, Smoke — Hm
(ii) Brass — Ht, Fog — Ht, Vinegar — Ht, Muddy water — Hm
(iii) Copper sulfate solution — Hm, Salt solution — Hm, Milk — Hm, Bronze — Hm
(iv) Muddy water — Ht, Milk — Ht, Blood — Ht, Brass — Hm
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Q 2
Question
Choose the correct options, and explain the reason for the correct and incorrect options.
Which among the following mixtures show the Tyndall Effect? A mixture of:
(a) air and dust particles
(b) copper sulfate and water
(c) starch and water
(d) acetone and water
(i) a and b (ii) b and d (iii) a and c (iv) c and d
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Q 3
Question
A mixture can be categorised as a solution, a suspension, or a colloid, each possessing distinct properties. Utilise the words or phrases provided in the box to fill in the Table 5.2. Words and phrases may be used more than once.
📦 Words and Phrases
Large-sized particles (more than 1000 nm in diameter); Particles remain evenly distributed; Small-sized particles (less than 1 nm diameter); Moderate-sized particles (1–1000 nm); Settles down when left undisturbed; Does not settle down; Scatters light; Separates by filtration; Transparent; Salt solution; Milk; Sand in water; Smoke; Heterogeneous mixture; Cannot be separated by filtration; Mud; Butter; Brass.
Complete the Table 5.2.

Q 4
Question
Solve the following problems:
(i)
A cake recipe uses dry ingredients, namely 75 g of sugar for 420 g of all-purpose flour and 5 g of sodium hydrogencarbonate. Express the concentration of each component in the mixture using an appropriate method.
(ii)
A brass alloy contains 70% copper by mass. Calculate the quantities of copper and zinc present in 120 g of brass.
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Q 5
Question
The label on a cooking oil pack says one litre (910 g). If this oil is mixed with water, will it form a separate layer? If so, which substance will be on top? How will you separate the two layers? Also, draw the diagram of the apparatus used.
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Q 6
Question
Assertion (A):
Solutions do not exhibit the Tyndall effect.
Reason (R):
The particles in solutions are larger than 100 nm, so they cannot scatter light.
Choose the correct option:
(i) Both A and R are true, and R is the correct explanation of A.
(ii) Both A and R are true, but R is not the correct explanation of A.
(iii) A is true, but R is false.
(iv) A is false, but R is true.
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Q 7
Question
How would you separate the mixtures given in Table 5.3? Mention the reason for choosing your method. If a mixture cannot be separated, explain why.
Mixture
Method of separation
Reason for selection
Mud from muddy water
—
—
Plasma from other components in the blood sample
—
—
Naphthalene and sand
—
—
Chalk powder and common salt
—
—
Common salt and water
—
—
Oil from water
—
—
Pigments of the flower
—
—
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Q 8
Question
Two miscible liquids, A and B, are present in a mixture. The boiling point of A is 60 °C and the boiling point of B is 90 °C. Suggest a method to separate them. Also, draw a labelled diagram of the method suggested.
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Q 9
Question
Compare evaporation, crystallization and distillation. In which situation, would you prefer each of these over the others?
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Q 10
Question
Blood is an example of a colloidal mixture.
(i)
What would happen if blood behaved like a true suspension inside the body?
(ii)
In a blood sample, identify the dispersed phase and the dispersion medium.
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Q 11
Question
You are given a mixture of sand, common salt and naphthalene (Fig. 5.25a). The Fig. 5.25b depicts various steps used to separate the components of this mixture. Identify and write down the correct sequence of separation techniques.
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Q 12
Question
Why is distillation an effective method for separating a mixture of water and acetone?
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Q 13
Question
Answer the following questions with the help of the data given in Table 5.4.
Salts
10 °C
20 °C
30 °C
40 °C
60 °C
80 °C
Potassium nitrate
21
32
45
62
106
167
Sodium chloride
36
36
36.3
36.5
37
37
Potassium chloride
35
35
37.4
40
46
54
Ammonium chloride
24
37
41
41
55
66
(i)
What mass of potassium nitrate would be needed to prepare its saturated solution in 50 g of water at 40 °C?
(ii)
A student makes a saturated solution of potassium chloride in water at 80 °C and leaves the solution to cool at room temperature (25 °C). What would she observe as the solution cools? Explain.
(iii)
What is the effect of a change in temperature on the solubility of salts? Also, compare the changes in the solubility of the four given salts with increasing temperature from 10 °C to 80 °C.
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Q 14
Question
Three students, A, B and C, are preparing sugar solutions for an experiment:
Student A dissolves 20 g of sugar in 80 g of water.
Student B dissolves 20 g of sugar in 100 g of water.
Student C dissolves 30 g of sugar in 80 g of water.
(i)
Calculate the mass percentage (% m/m) concentration of sugar in each student’s solution.
(ii)
Whose solution is the most concentrated? Explain why.
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Q 15
Question
Examine Fig. 5.26.
(i)
Identify the separation technique marked as ‘S’.
(ii)
Label the apparatus A, B and C.
(iii)
Which of the following mixtures can be separated by the technique identified above? Use the data given in Table 5.5. Mixtures:
(a) water — acetone
(b) water — salt
(c) acetone — alcohol
(d) sand — salt
(e) alcohol — chloroform
(f) alcohol — benzene
Solvent
Water
Acetone
Alcohol
Chloroform
Benzene
Temperature (°C)
100 °C
56 °C
78 °C
61 °C
80 °C
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Seven projects to take the chapter further, on your own or with your class.
🔦
Project 1 — Demonstrate the Tyndall Effect
Question
Demonstrate the Tyndall effect using different colloids. Create a series of experiments showcasing how light scatters in colloids making the beam visible. Use laser pointers (
Safety first:
Use it under the supervision of an adult), flashlights, or other light sources for your demonstrations.
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Key Points
Seeing the path of light tells us a mixture is a colloid, not a true solution.
Key Points
Clean water and the salt solution show no visible beam — both are true solutions.
Milk and the starch solution show a bright, visible beam — both are colloids.
A visible beam path is the one-second test for a colloid.
💎
Project 2 — Grow Crystals of Different Compounds
Question
Make crystals of different compounds (common salt, epsom salt, sugar, borax, nickel sulfate, etc.). Observe them under a magnifying glass or a microscope. Note down their colours and shapes.
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Key Points
Every pure compound has its own fixed, geometric crystal shape.
Key Points
Common salt forms crystals shaped like cubes.
Sugar forms crystals that look more like long grains.
Recording colour, shape and formation time in a table makes the differences easy to compare.
🍃
Project 3 — Is There Green Pigment Hidden in Red Leaves?
Question
Do red leaves also contain green pigments? Investigate it using paper chromatography.
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Key Points
Looking red does not mean a leaf has no green pigment — the red colour is simply strong enough to hide it.
Key Points
A red leaf's chromatogram usually shows a green spot too, alongside the red.
The result depends on the leaf and the solvent used, so a clean separation is not guaranteed every time.
🎨
Project 4 — Count the Components by Chromatography
Question
You can try chromatography to find the number of components present in a food colour (green, orange, yellow, etc.) or in coloured mouth fresheners (fennel seeds).
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Key Points
A single colour we see with the naked eye often hides two or three separate components.
Key Points
Running chromatography on the sample splits the one visible colour into its component spots.
The number of spots tells us how many components actually made up that colour.
🃏
Project 5 — Design a Separation-Technique Game
Question
Design an educational game where players identify and apply separation techniques to different mixtures through interactive challenges and hands-on activities.
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Key Points
Turning Table 5.3 into a card game is a fun way to revise every separation technique in this chapter.
Key Points
Each card pairs a mixture with its correct separation technique and the reason behind it.
Table 5.3 of this chapter is a ready-made starting list of mixtures to use.
⛺
Project 6 — Clean Water While Camping
Question
If you are camping outdoors and running short on clean water, you can obtain clean water by distillation. Can you think of a set-up with the items available to you?
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Key Points
This home-made set-up is distillation at work — form the vapour, then condense it.
Key Points
Water vapour rising from the dirty water condenses on the cool plastic sheet.
The condensed drops slide down the sheet's slope and collect in the bowl as clean water.
Weak sunlight means the water collects very slowly, so plan for it a day ahead, not as an instant fix.
💻
Project 7 — Online Simulations
Question
To learn more about the states of matter and concentration of solutions, you can explore the links given below:
states-of-matter-basics
,
concentration
.
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Key Points
The PhET simulations let you watch concentration change live, right on your own screen.
Key Points
One simulation covers states of matter.
The other lets you change concentration and see the effect instantly.

The chapter ends on an open question —
“Can we create artificial blood that works just as real blood for all patients?”
Nobody has that answer yet. Maybe, one day, you will.