NCERT Solutions Curiosity Chapter 8 Science • Society • Interdisciplinary Projects — Discover, design, and debate

Book page 133 Updated on2026-09-05

Q1.

Design and create comic strips from real-life examples to differentiate between elements, compounds, and mixtures with diagrams and illustrate their properties and uses.

Answer

Build the strip around one story, not three separate ones — that is what makes the difference stand out.

A good comic strip must contain:

three characters, one for each category, with their particles drawn: an element as identical circles, a compound as two kinds of circles joined together, a mixture as two kinds lying loose;
at least one real example of each from your own home;
one property that gives each away — a magnet, a filter, a change of colour on heating;
one use of each in daily life;
a closing panel with the rule the reader should carry away.

Sample strip (six panels):

The kitchen. Meera picks up a steel spoon, a packet of salt and a bowl of sprout salad. "Three things — are they the same kind of stuff?"
Salad speaks: "Look, you can pick out my moong, my chana, my onion, my tomato. I am a mixture — everyone here keeps their own taste, and you can pull us apart."
Salt speaks: "I am made of sodium, a soft metal, and chlorine, a dangerous gas, joined in a 1 : 1 ratio. I am a compound — and I am safe to eat, which neither of them is. Try separating me with a sieve!"
The spoon speaks: "Careful — I am stainless steel, which is iron, nickel, chromium and a little carbon. I look like one substance, but I am a uniform mixture, an alloy."
Enter Gold, from Meera's mother's ring: "I am an element. Break me down as much as you like — you will still get gold."
The rule panel: "Can I separate it physically? Then it is a mixture. If not — can it be broken into simpler substances at all? If yes, a compound; if no, an element."

Tip: Draw the particles in every panel, in the same style. Readers remember the picture of the particles long after they forget the words.

Q2.

Search for discoveries of some elements (such as phosphorus, sodium), compounds (such as penicillin) and mixtures (such as brass, bronze, stainless steel). Present your findings in the class.

Answer

Organise the search by asking the same four questions of each substance, so your presentation has a shape: who found it, when, how they found it, and why it mattered.

Substance	Type	Points worth reporting
Phosphorus	Element	Found in the 17th century by an alchemist who was boiling down urine while searching for gold; it glowed in the dark, which is how it got its name. A reminder that many discoveries were accidents.
Sodium	Element	Obtained early in the 19th century by passing electricity through a molten compound — the same idea you used in Activity 8.3 on water. Electricity became the tool that prised open compounds.
Penicillin	Compound	Noticed when a mould accidentally contaminated a dish of bacteria and killed them. It became the first widely used antibiotic and has saved millions of lives.
Bronze	Mixture (alloy)	Copper and tin. So important that an entire age is named after it. In India it is kamsya, described in the Charaka Samhita as copper (4 parts) with tin (1 part).
Brass	Mixture (alloy)	Copper and zinc — golden in colour, easy to shape, and still the metal of choice for lotas, bells and door fittings.
Stainless steel	Mixture (alloy)	Iron, nickel, chromium and a little carbon. Invented while looking for a steel that would not rust in gun barrels; stronger and more durable than pure iron.

Tip: End the presentation with a pattern rather than a list: elements were mostly discovered by taking things apart, compounds by observing an effect and then chasing its cause, and alloys by craftspeople trying to make a better tool.

Q3.

Let us search: Read labels on items like detergents or snacks, and try to list the mixtures and compounds they contain.

Answer

Take the packet to the light and read the "Ingredients" line. Then sort each name by asking: is this one substance, or several mixed?

Sample answer — a packet of biscuits and a packet of detergent:

Item	Named on the label	Compound or mixture
Biscuits	Sugar	Compound
	Salt (sodium chloride)	Compound
	Baking soda	Compound
	Raising agent (baking powder)	Mixture — baking soda and tartaric acid
	Wheat flour, edible vegetable oil, milk solids	Mixtures
	The biscuit itself	Mixture
Detergent	Sodium carbonate (washing soda)	Compound
	Sodium chloride	Compound
	Perfume, colour, optical brightener	Mixtures
	The detergent powder itself	Mixture

What the exercise teaches: Every packaged product you buy is a mixture, however "pure" the front of the pack claims to be. The individual ingredients listed on the back are the pure substances — and they are almost always compounds, because free elements are rare in everyday products.

Tip: Look for a percentage or a "not more than" figure. A compound has a fixed composition, so a printed proportion is a sign that you are reading about a mixture.

Q4.

Work in groups: Each group will pretend to be in the role of either an element, a compound, or a mixture. Debate which category among them is the most important.

Answer

The honest answer is that no one category can win — but the debate is worth having, because the argument each side must build is the chapter itself. Prepare a case, not a slogan.

Team	Strongest arguments
Elements	"We are the building blocks of all matter. There are only 118 of us and everything else — every compound, every mixture — is made from us. Iron and aluminium build your bridges, buildings and vehicles; more than 45 of us go into a single mobile phone."
Compounds	"An element on its own is often useless or dangerous. Sodium is a soft metal and chlorine a hazardous gas, but together we are the salt that is essential for your life. We are the medicines, the vaccines and the fertilisers that feed a growing population — and we are water."
Mixtures	"You cannot breathe an element; you breathe air. You cannot build a city out of pure iron; you build it out of steel, concrete and wood. Alloys like stainless steel are stronger and more durable than pure iron — and we can be tuned, because our proportions are not fixed."

Sample closing statement (for the chairperson): "Elements are the alphabet, compounds are the words, and mixtures are the sentences we actually speak. Remove the elements and there is nothing to build with; remove the compounds and there is no water, no salt, no medicine; remove the mixtures and there is no air to breathe. The question is not which is most important, but which one you need for a given job — and knowing that is what this chapter has taught us."

Tip: Score the debate on evidence, not volume. Every claim should point to something from the chapter — the electrolysis of water, the iron–sulfur experiment, lime water, alloys or minerals.

Was this helpful? Report an error