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NCERT Solutions Curiosity Chapter 1 Science is a process — In-text Questions

Book page 2 Updated on2026-09-05

Q1.
How do things work?
Answer

This is the first of the three deeper questions Grade 7 asks. A “how” question asks for the mechanism — the chain of steps by which something happens.

The way to answer it is always the same:

  1. Break the thing into parts. A torch = cell + switch + wires + bulb.
  2. Find out what each part does. The cell pushes the charge, the wires carry it, the bulb’s thin filament glows.
  3. Follow the chain from the first part to the last, and check it by changing one part at a time.

Some “how” questions waiting for you in this book:

  • How does a bulb glow when it is joined to a cell?
  • How does heat travel from the flame to the handle of a steel kadhai?
  • How does the food you eat reach every corner of your body?
  • How does water from the sea end up in a well in your village?
Why this question matters: once you know how something works, you can predict it, repair it and improve it. A cycle mechanic who knows how a brake works can fix any brake; someone who has only memorised the parts cannot.
Q2.
Why do events happen the way they do?
Answer

A “why” question asks for the cause — the reason an event turned out this way and not some other way. “How” describes the steps; “why” explains the reason behind them.

EventThe “how” (steps)The “why” (cause)
Ice in a glass meltsHeat moves from the warm air into the iceHeat always flows from the hotter body to the colder one
A shadow is shortest at noonThe shadow shrinks all morning, then growsThe Sun is highest in the sky at noon
Mangoes ripen faster in summerThe fruit softens and sweetens soonerChanges speed up when things are warmer
Why it happens: a “why” answer is useful only when it can be tested. If the reason is “heat flows from hot to cold”, then wrapping the glass in a thick towel should slow the melting — and it does. A reason that cannot be tested is not yet science.
Tip: When you are stuck, ask “why” twice. Why does the ice melt? Because heat reaches it. Why does heat reach it? Because the air around is hotter. The second “why” usually gets you the real answer.
Q3.
And what can we learn from the patterns that we see in nature?
Answer

A pattern is something that repeats in a regular way. Patterns are precious in science for three reasons.

  • They let us predict. Day follows night, the Moon waxes and wanes in about 29–30 days, the monsoon reaches Kerala around the start of June. Because these repeat, a farmer can plan sowing and a fisherman can plan a trip.
  • They point to a hidden rule. Day and night repeat because the Earth spins on its axis. The pattern is what we see; the spin is the rule behind it.
  • They let us classify. Notice that copper, iron and aluminium all shine, conduct electricity and can be beaten into sheets — that repeated set of properties is why we group them together as metals.

Patterns you can spot today: the veins of a leaf branching in the same way as the branches of the tree, the six-sided cells of a honeycomb, the spiral of seeds in a sunflower, the same rangoli motif turned four times around a point.

Why it happens: nature repeats because the same causes act again and again. Wherever you find a repeat, there is a rule waiting to be discovered — and a break in the pattern is even more interesting, because it means a new cause has entered.
Q4.
Why are some fruits sour?
Answer

Because they contain acids. A sour taste is the tongue’s way of reporting an acid, and every sour fruit or food you know carries one.

Sour foodAcid it contains
Lemon, orange, mausambiCitric acid
Tamarind (imli)Tartaric acid
Curd, buttermilkLactic acid
Vinegar (sirka)Acetic acid
AmlaAscorbic acid (vitamin C)

The same fruit also changes its sourness as it grows. A raw green mango is sharply sour; the ripe one is sweet. As a fruit ripens, much of the acid is used up and starch is converted into sugar — so sourness falls and sweetness rises.

Why it happens: sourness is a property of the material, exactly like shine or hardness. Because acids behave in a fixed way — they turn blue litmus red and lose their sourness when mixed with a base — sourness can be used to sort substances into groups. That is why the very next chapter of this book begins with sour and bitter things.
Check it yourself: Squeeze a little lemon juice into a spoon of water and taste it. Now stir in a pinch of baking soda. The fizz and the loss of the sour taste tell you an acid has met a base.
Q5.
What happens when we wash a haldi stain on our school uniform?
Answer

The yellow haldi stain turns reddish-brown the moment soap or detergent touches it — the stain seems to get worse. Then, when you rinse it well with plenty of water, the red colour fades back to yellow, and with more washing the stain finally goes.

Haldi + water → stays yellow
Haldi + soap solution (a base) → turns red-brown
Red-brown stain + water or lemon juice (an acid) → yellow again
Why it happens: turmeric contains curcumin, which is a natural indicator — a substance that shows one colour with acids and neutral things, and a different colour with bases. Soap and detergent solutions are basic, so they flip the curcumin to red-brown. Water or a drop of lemon juice brings the yellow back. Nothing has been spoiled; the colour is simply reporting what kind of substance touched it.
Try This: Soak a strip of blotting paper in a little turmeric paste, dry it, and you have a home-made haldi indicator strip. Touch it with soap water, lemon juice, curd and baking-soda water and note the colours. You will use exactly this trick in the chapter on acids and bases.
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