CBSE Class 7 Science Chapter 05 Changes Around Us Physical And Chemical MCQs Set 02

Practice MCQs for Class 7 Science Chapter 05 Changes Around Us Physical And Chemical

Review structured MCQ sets for Class 7 Science Chapter 05 Changes Around Us Physical And Chemical. Built according to official CBSE guidelines, these downloadable questions support daily revision and core concept reinforcement.

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Question: We notice changes happening around us using several senses. Which set of senses is used for this purpose?
A. Only sight and touch
B. Sight, smell, touch, hearing, and taste
C. Smell and hearing only
D. Only sight and taste
Show Answer & Explanation

Answer: (B) Sight, smell, touch, hearing, and taste

Explanation:
The text explicitly says we observe changes with the help of sight, smell, touch, hearing, and taste — all five senses, not just a couple of them.

Question: At the start of the chapter, four students talk about melting ice, a warm water bottle, a blooming bud, and a spotted banana. What is the purpose of these opening examples?
A. To introduce the idea that everyday changes can be classified as physical or chemical
B. To explain how temperature is measured
C. To demonstrate the states of matter in detail
D. To show how plants grow over several months
Show Answer & Explanation

Answer: (A) To introduce the idea that everyday changes can be classified as physical or chemical

Explanation:
These everyday observations set up the chapter's central question — what kinds of changes are these — which the chapter then answers by introducing physical and chemical changes.

Question: Wood, paper, and kerosene are all described as combustible substances. What does this term actually mean?
A. Substances that dissolve quickly in water
B. Substances capable of catching fire and burning
C. Substances that never react with any gas
D. Substances that only melt but never burn
Show Answer & Explanation

Answer: (B) Substances capable of catching fire and burning

Explanation:
A combustible substance is one that undergoes combustion — it reacts with oxygen and burns, often releasing heat and light.

Question: In Activity 5.1, rolling small dough balls into chapatis is listed as a change to observe. Once flattened, can the chapati be rolled back into its original ball shape?
A. Yes, because no new substance was formed
B. No, this shape change cannot be undone even though it is a physical change
C. No, because a chemical reaction has occurred
D. Yes, but only after heating it again
Show Answer & Explanation

Answer: (B) No, this shape change cannot be undone even though it is a physical change

Explanation:
Flattening dough only changes its shape and size, so no new substance forms — it stays a physical change. But that particular shape change happens to be one you cannot practically reverse by hand, unlike melting ice, which can be refrozen.

Question: Rising use of fuel in vehicles like cars and aeroplanes has a long-term consequence for the environment. What is that consequence?
A. A steady rise in carbon dioxide levels in the atmosphere
B. A decrease in atmospheric oxygen to zero
C. Faster rusting of all metal objects worldwide
D. Formation of new rock layers within a few years
Show Answer & Explanation

Answer: (A) A steady rise in carbon dioxide levels in the atmosphere

Explanation:
Burning more fuel over the years steadily adds more carbon dioxide to the air, which the chapter flags as a human-driven environmental impact.

Question: Why is the drying of paint on walls and furniture classified as an undesirable change?
A. It permanently damages the furniture's shape
B. It releases substances into the air through evaporation, contributing to pollution
C. It causes the paint to catch fire spontaneously
D. It converts the paint into a combustible gas
Show Answer & Explanation

Answer: (B) It releases substances into the air through evaporation, contributing to pollution

Explanation:
As paint dries, evaporating substances escape into the air, and the chapter links this to atmospheric pollution — making it an undesirable, though common, change.

Question: Which sequence correctly describes what happens to the wax when a candle is lit, as explained in the chapter?
A. The wax melts, travels up the wick, evaporates, and its vapour then burns
B. The wax evaporates first and only melts afterward
C. The solid wax burns directly without melting
D. The wax solidifies before it ever melts or burns
Show Answer & Explanation

Answer: (A) The wax melts, travels up the wick, evaporates, and its vapour then burns

Explanation:
• Melting: solid wax turns liquid near the flame
• Wicking: liquid wax is drawn up the wick
• Evaporation: heat turns the liquid wax into vapour
• Combustion: the wax vapour finally burns to sustain the flame

Question: In Activity 5.8, all the changes discussed earlier are sorted into two broad groups based on a single criterion. What is that criterion?
A. Whether the change is desirable or undesirable
B. Whether the change is physical or chemical
C. Whether the original substance can be brought back or not
D. Whether the change happens quickly or slowly
Show Answer & Explanation

Answer: (C) Whether the original substance can be brought back or not

Explanation:
Table 5.2 asks students to record a simple yes or no for each change, sorting them into those that can be reversed and those that cannot.

Question: In the yeast-and-sugar exploratory project, a balloon tied over the bottle gradually inflates by itself after an hour. What does this observation suggest is happening inside?
A. Water inside is slowly evaporating into steam
B. A chemical reaction between yeast and sugar is producing a gas
C. Air is leaking backward from the balloon into the bottle
D. The yeast is simply dissolving without any reaction
Show Answer & Explanation

Answer: (B) A chemical reaction between yeast and sugar is producing a gas

Explanation:
The gradual swelling of the balloon points to gas being generated inside the bottle, which fits with a chemical change occurring between the yeast and the sugar solution rather than a simple physical process.

Question: How does the chapter define the natural process called erosion?
A. The breaking down and transport of rock pebbles, soil, and sediments by forces like wind and flowing water
B. The reaction of iron with moist air to form a brown coating
C. The melting of rocks due to heat from within the earth
D. The hardening of loose soil particles into large rocks
Show Answer & Explanation

Answer: (A) The breaking down and transport of rock pebbles, soil, and sediments by forces like wind and flowing water

Explanation:
Erosion is described as sediments and broken rock material being carried from one place to another by natural agents such as wind and rivers.

Question: In the exploratory project, a hidden message written in lemon juice reappears in brown letters once the paper is warmed. What actually causes the writing to become visible?
A. The paper simply dries out and changes shade uniformly
B. Heat brings about a chemical change in the lemon juice residue on the paper
C. The iron leaves a brown mark wherever it touches the paper
D. The lemon juice reacts with the surrounding air to form rust
Show Answer & Explanation

Answer: (B) Heat brings about a chemical change in the lemon juice residue on the paper

Explanation:
Warming the paper triggers a chemical change in the dried lemon juice, turning it brown only where the invisible ink was written — a change that cannot simply be undone by cooling the paper.

Question: What practical use does the milky colour change of lime water serve?
A. It measures how hot a liquid is
B. It is used as a test to detect carbon dioxide gas
C. It shows whether a substance can catch fire
D. It indicates the presence of oxygen in a mixture
Show Answer & Explanation

Answer: (B) It is used as a test to detect carbon dioxide gas

Explanation:
Both the breath-blowing activity and the vinegar-baking soda experiment use the same clue — lime water turning milky confirms that carbon dioxide gas is present.

Question: The white substance formed when carbon dioxide reacts with lime water is described as 'insoluble'. What does this term convey about the substance?
A. It dissolves completely and rapidly in water
B. It does not dissolve in water and settles at the bottom
C. It evaporates as soon as it forms
D. It keeps changing colour over time
Show Answer & Explanation

Answer: (B) It does not dissolve in water and settles at the bottom

Explanation:
Because calcium carbonate does not dissolve, it collects as a settled layer at the bottom of the container, which is what makes the water look cloudy before it eventually clears at the top.

Question: Why can chopped vegetables never be restored to their original whole shape?
A. Because chopping creates a brand-new chemical substance
B. Because the change in size and shape brought about by chopping cannot be undone
C. Because vegetables lose all moisture instantly when cut
D. Because chopping always triggers decomposition right away
Show Answer & Explanation

Answer: (B) Because the change in size and shape brought about by chopping cannot be undone

Explanation:
Chopping is a physical change, since no new substance forms, but it is still listed among the changes that cannot be reversed simply because the pieces cannot be rejoined into their original form.

Question: In the exercise about Nalini's bicycle, brown deposits appear on the cycle's metal handle over time. What causes this, and what kind of change does it represent?
A. Dust settling on the handle, a physical change
B. Rusting caused by the metal reacting with oxygen and moisture, a chemical change
C. Wearing off of chrome plating, a reversible physical change
D. Sunlight bleaching the metal, a physical change
Show Answer & Explanation

Answer: (B) Rusting caused by the metal reacting with oxygen and moisture, a chemical change

Explanation:
The brown deposits match the description of rust, which forms when iron reacts with oxygen and moisture in the air — a chemical change because a new substance, iron oxide, is created.

Question: Which pair of statements correctly captures what happens during a physical change?
A. The state of the substance may or may not change, and no new substance forms
B. A new substance with different properties is always formed
C. The substance undergoes a chemical reaction that changes its composition
D. The substance loses its original identity permanently
Show Answer & Explanation

Answer: (A) The state of the substance may or may not change, and no new substance forms

Explanation:
A physical change alters only properties like shape, size or state, while the substance itself stays the same underneath. It does not involve a chemical reaction or the creation of a new substance, ruling out the other options.

Question: Using a synthetic blanket or cloth to smother a fire on someone's clothing is specifically cautioned against. What is the reason given for this?
A. Synthetic material can melt and stick to the skin, worsening the injury
B. Synthetic material burns faster and spreads the fire
C. Synthetic material reacts chemically with the flame to release toxic gas
D. Synthetic material is not thick enough to cut off the air supply
Show Answer & Explanation

Answer: (A) Synthetic material can melt and stick to the skin, worsening the injury

Explanation:
Cutting off air with a blanket stops combustion, but a synthetic blanket poses its own danger since it can melt onto the person's skin rather than simply smothering the flame.

Question: Which of these is NOT a cause of the physical breaking up of rocks during weathering?
A. Roots of trees growing into cracks
B. Freezing of water trapped inside cracks
C. Temperature changes linked to climate
D. Strong winds directly carrying rocks away
Show Answer & Explanation

Answer: (D) Strong winds directly carrying rocks away

Explanation:
The text credits root growth, freezing water, and climatic temperature swings for physically fracturing rocks into sediments.
• Wind carrying away already-broken material is described separately, under erosion, not as a cause of the initial breaking.

Question: When flowing water or wind slows down, such as in a lake or ocean, what eventually happens to the sediments it has been carrying?
A. They dissolve completely and disappear
B. They settle at the bottom and harden over time into new rocks
C. They evaporate along with the water
D. They react chemically to form soil instantly
Show Answer & Explanation

Answer: (B) They settle at the bottom and harden over time into new rocks

Explanation:
As the carrying force weakens, transported material drops out of suspension and accumulates at the bottom. Over long spans of time, this settled material compacts and hardens, eventually forming new rock layers.

Question: A hillside collapses suddenly, sending loose rocks and soil sliding downward in a landslide. How is this kind of erosion classified?
A. As a chemical change, since new minerals form
B. As a physical change, since only movement and breaking occur
C. As neither a physical nor chemical change
D. As a change that is always reversible
Show Answer & Explanation

Answer: (B) As a physical change, since only movement and breaking occur

Explanation:
Landslides simply shift and fragment material without producing any new substance, so the chapter places this under physical change rather than chemical change.

Question: Milk turning into curd involves a change in its properties and composition. Why is this treated as a chemical rather than a physical change?
A. Because milk simply changes its shape and volume
B. Because a new substance with different properties is formed and cannot be turned back into milk
C. Because milk only becomes colder during the process
D. Because no new substance forms, only the texture changes
Show Answer & Explanation

Answer: (B) Because a new substance with different properties is formed and cannot be turned back into milk

Explanation:
Curdling produces curd, a substance distinct from milk in taste, texture and composition, and once formed it cannot revert to milk. Since a genuinely new substance appears, this fits the chapter's definition of a chemical change rather than a mere physical one.

Question: When a strip of magnesium is burnt in air, what does the resulting new substance look like?
A. A shiny grey liquid
B. A white-coloured powder
C. A black sooty residue
D. A colourless gas
Show Answer & Explanation

Answer: (B) A white-coloured powder

Explanation:
Magnesium ribbon combines with oxygen during burning to give off heat and light while leaving behind magnesium oxide, seen as a white powder.

Question: Suppose the baking soda test is repeated by mixing it with plain water instead of vinegar. What result would indicate that this time no chemical change has occurred?
A. Fizzing bubbles and a strong smell appear immediately
B. The mixture turns milky on its own
C. No bubbles form, showing the soda has simply dissolved
D. The water evaporates completely within seconds
Show Answer & Explanation

Answer: (C) No bubbles form, showing the soda has simply dissolved

Explanation:
Baking soda reacts with the acid in vinegar to release carbon dioxide gas, producing visible fizzing. With water there is no acid to react with, so the soda just dissolves without bubble formation, meaning it is only a physical change.

Question: Among the changes commonly listed for prediction exercises, dissolving sugar in water is one many students find tricky to classify as reversible or not. Why can this change generally be considered reversible?
A. Because the sugar disappears permanently and cannot be recovered
B. Because heating the solution to evaporate the water leaves the sugar behind again
C. Because sugar reacts chemically with water to form a new substance
D. Because stirring the mixture changes the sugar into a different compound
Show Answer & Explanation

Answer: (B) Because heating the solution to evaporate the water leaves the sugar behind again

Explanation:
Sugar dissolving in water is a physical change, not a chemical one, since the sugar molecules simply spread through the water without altering their identity. Evaporating away the water afterwards leaves the original sugar behind, showing the process can be reversed.

Question: In the classification exercise where changes are sorted into physical, chemical, or an overlapping category, what kind of change belongs in the overlapping middle section?
A. A change that is neither physical nor chemical
B. A change, like burning a candle, that involves both physical and chemical processes together
C. Only changes that can be reversed
D. Only changes that release heat
Show Answer & Explanation

Answer: (B) A change, like burning a candle, that involves both physical and chemical processes together

Explanation:
Some processes combine both types of change within a single event.
• Melting and evaporation of wax are physical changes.
• Burning of the wax vapour is a chemical change.
• Because both occur together, such a process is placed in the shared middle zone rather than purely under physical or chemical.

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Multiple Choice Questions (MCQs) for Class 7 Science Chapter 05 Changes Around Us Physical And Chemical

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