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By Swati Singh
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Updated on 17 Dec 2025, 14:57 IST
CBSE Class 6 Science Chapter 6, Changes Around Us, teaches students about the different types of changes that happen in the world. This chapter helps students understand how things can change in shape, size, or state and whether these changes can be undone.
Some changes can be reversed, meaning we can get the original thing back. For example, when ice melts into water, we can freeze the water back into ice. These are called reversible changes. Other changes cannot be reversed, like when paper burns and turns into ash. These are called irreversible changes.
The chapter also talks about physical changes, where only the appearance of the object changes but not what it is made of. For example, tearing a piece of paper is a physical change. On the other hand, chemical changes create new substances. For example, when we cook food, it changes chemically and cannot be turned back into raw ingredients.
Multiple Choice Questions (MCQs) are used to help students practice what they have learned in the chapter. These questions test their understanding and help them remember important points. MCQs in this chapter cover examples and definitions of different types of changes, helping students think about how and why changes happen.
In summary, Chapter 6 of CBSE Class 6 Science helps students learn about the different kinds of changes that occur around us every day. Through easy-to-understand lessons and practice questions, students gain a better understanding of science and how it explains the world we live in. This chapter lays the groundwork for future science learning and helps students become more curious and thoughtful observers of their environment.
Which of the following changes can be reversed?
a) Raw egg to boiled egg
b) Wet clothes to dry clothes
c) Bud to flower
d) Cow dung to biogas
Answer: b) Wet clothes to dry clothes
Explanation: Wet clothes can be dried and then made wet again, making it a reversible change. All other changes are irreversible.
Which of the following changes is not reversible?
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a) Milk to paneer
b) Cold milk to hot milk
c) Yarn to knitted sweater
d) Wet clothes to dry clothes
Answer: a) Milk to paneer
Explanation: Once milk is converted into paneer (a new substance), it cannot be changed back into milk.
Metal rim is fixed to the wooden cart wheel by
a) heating the metal rim
b) heating the wooden wheel
c) cooling the metal rim
d) cooling the wooden wheel
Answer: a) heating the metal rim
Explanation: Heating the metal rim causes it to expand, allowing it to fit around the wheel.
On heating a metal rim, it
a) expands
b) contracts
c) depends on how much it is heated
d) depends on the type of metal
Answer: a) expands
Explanation: Metals expand when heated.
Which of the steps while burning a candle is not reversible?
a) Melting of solid wax
b) Liquid wax changing into vapours
c) Wax vapour burning into flame
d) All of these
Answer: c) Wax vapour burning into flame
Explanation: Burning of wax vapours is an irreversible process.
What are the ways to make a change happen?
a) Heating a substance
b) Cooling a substance
c) Mixing a substance with another substance
d) All of these
Answer: d) All of these
Explanation: Changes can be made by heating, cooling, or mixing substances.
Rusting of iron is an example of
a) slow change
b) fast change
c) reversible change
d) physical change
Answer: a) slow change
Explanation: Rusting of iron occurs slowly over time.
Conversion of a solid to a liquid by heating is called
a) evaporation
b) melting
c) condensation
d) freezing
Answer: b) melting
Explanation: Heating a solid causes it to melt into a liquid.
Which of the following is not a man-made change?
a) Change of day and night
b) Burning of fuels
c) Drying of clothes
d) Tearing of paper
Answer: a) Change of day and night
Explanation: The change of day and night is a natural process.
Which of the following is a chemical change?
a) Evaporation of water
b) Burning of fuels
c) Moving of a wheel
d) Breaking of a brick
Answer: b) Burning of fuels
Explanation: Burning of fuels results in a chemical change.
What happens when water is heated in a pan?
a) Quantity of the water in the pan increases
b) Water starts to cool down
c) Quantity of the water in the pan decreases
d) Water changes into solid
Answer: c) Quantity of the water in the pan decreases
Explanation: Heating water causes it to evaporate, reducing its quantity in the pan.
The shape and size of a pencil and eraser change with repeated use. Is it possible to undo this change?
a) Yes, to some extent
b) No
c) Maybe
d) Data insufficient
Answer: b) No
Explanation: Once a pencil and eraser have changed shape and size with use, the change is permanent and cannot be reversed.
Which of the following is the name given to the process of converting a solid into a liquid?
a) Condensation
b) Melting
c) Evaporation
d) Freezing
Answer: b) Melting
Explanation: The process of converting a solid into a liquid by heating is called melting.
Rusting of iron is an example of
a) Reversible change
b) Irreversible change
c) Physical change
d) None of the above
Answer: b) Irreversible Change
Explanation: Rusting of iron is a permanent and irreversible change.
What kind of change is expansion?
a) Irreversible
b) Permanent
c) Reversible
d) All of the above
Answer: c) Reversible
Explanation: When an object is heated and expands, it can return to its original size when cooled, making it a reversible change.
Which of the following processes is responsible for recovering salt from water?
a) Condensation
b) Evaporation
c) Crystallization
d) Melting
Answer: b) Evaporation
Explanation: Evaporation removes water, leaving the salt behind.
Which of the following is not an example of a change that occurs when two substances are mixed?
a) Salt dissolved in water
b) Sand-water mixture
c) Sugar dissolved in water
d) Matchstick combustion
Answer: d) Matchstick combustion
Explanation: Combustion of a matchstick is not a result of mixing substances but of burning.
A chemical change involves
a) Both a change in state and a change in composition.
b) Only a state change
c) Only a colour change
d) None of the above
Answer: a) Both a change in state and a change in composition
Explanation: A chemical change results in a new substance with different physical and chemical properties.
Which of the following changes in the water state is a physical change?
a) Melting
b) Condensation
c) Boiling
d) All of the above
Answer: d) All of the above
Explanation: All these processes involve changes in the state of water without forming a new substance.
How is clothing drying a reversible change?
a) Because the dried clothes cannot be re-wet
b) Because dry clothing can become wet again
c) Because all of the water from the clothes had evaporated
d) All of the above
Answer: b) Because dry clothing can become wet again
Explanation: Dry clothes can be made wet again, making the process reversible.
Which of the following is an irreversible change?
a) Cutting of paper
b) Freezing of water
c) Burning of wood
d) Melting of butter
Answer: c) Burning of wood
Explanation: Burning wood produces ash and gases that cannot be changed back into wood, making it an irreversible change.
What kind of change occurs when iron rusts?
a) Physical change
b) Reversible change
c) Chemical change
d) Temporary change
Answer: c) Chemical change
Explanation: Rusting of iron is a chemical change where iron reacts with oxygen to form iron oxide.
Which process can be reversed by simple physical means?
a) Making curd from milk
b) Evaporation of water
c) Cooking of food
d) Rusting of iron
Answer: b) Evaporation of water
Explanation: Evaporated water can be condensed back into liquid water, making it a reversible process.
Which of the following is a man-made change?
a) Erosion of soil
b) Growth of a plant
c) Construction of a building
d) Rotation of Earth
Answer: c) Construction of a building
Explanation: Construction of a building is an activity carried out by humans, making it a man-made change.
Which change involves only a change in physical state but not in composition?
a) Boiling of water
b) Burning of coal
c) Fermentation of sugar
d) Digestion of food
Answer: a) Boiling of water
Explanation: Boiling water changes its state from liquid to gas without altering its chemical composition.
Which of the following describes a reversible physical change?
a) Dissolving sugar in water
b) Baking a cake
c) Burning a candle
d) Rusting of iron
Answer: a) Dissolving sugar in water
Explanation: Dissolved sugar can be recovered by evaporating the water, making it a reversible physical change.
Which of the following is an example of a temporary change?
a) Ironing clothes
b) Cutting a tree
c) Baking bread
d) Digesting food
Answer: a) Ironing clothes
Explanation: Ironed clothes can become wrinkled again, making it a temporary change.
Which process is an example of a chemical change?
a) Melting ice
b) Boiling water
c) Photosynthesis
d) Shredding paper
Answer: c) Photosynthesis
Explanation: Photosynthesis is a chemical process where plants convert carbon dioxide and water into glucose and oxygen using sunlight.
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Which of the following is a physical change that cannot be easily reversed?
a) Melting of chocolate
b) Breaking of a glass bottle
c) Dissolving salt in water
d) Sublimation of dry ice
Answer: b) Breaking of a glass bottle
Explanation: Once a glass bottle is broken, it cannot be easily reversed to its original form.
Which of the following changes is not considered a physical change?
a) Crushing a can
b) Boiling an egg
c) Freezing water
d) Chopping wood
Answer: b) Boiling an egg
Explanation: Boiling an egg results in a chemical change as the proteins in the egg undergo a chemical transformation.
Which of the following changes occurs naturally?
a) Melting of ice in a freezer
b) Growth of a baby
c) Painting a wall
d) Tearing a paper
Answer: b) Growth of a baby
Explanation: The growth of a baby is a natural change that occurs over time.
Which process involves a change in both state and composition?
a) Freezing of water
b) Melting of wax
c) Rusting of iron
d) Dissolving salt in water
Answer: c) Rusting of iron
Explanation: Rusting of iron involves a chemical change where iron reacts with oxygen and water to form iron oxide, changing both its state and composition.
Which change is associated with the absorption of energy?
a) Freezing water into ice
b) Melting ice into water
c) Burning wood
d) Rusting iron
Answer: b) Melting ice into water
Explanation: Melting ice absorbs heat energy from its surroundings to change from a solid to a liquid state.
What type of change is associated with the breaking of chemical bonds and formation of new substances?
a) Physical change
b) Chemical change
c) Temporary change
d) Reversible change
Answer: b) Chemical change
Explanation: A chemical change involves the breaking of chemical bonds and the formation of new substances with different properties.
Which of the following changes can be easily reversed?
a) Baking a cake
b) Freezing water into ice
c) Rusting of iron
d) Cooking vegetables
Answer: b) Freezing water into ice
Explanation: Freezing water into ice can be easily reversed by melting the ice back into water.
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"Changes around us" refers to the various alterations we observe in our environment, objects, materials, and even living organisms. These changes can be physical, chemical, or biological and occur naturally or due to human intervention.
Physical Changes: These are changes in the appearance, form, or state of a substance without altering its chemical composition. For example, melting ice, boiling water, or breaking glass.
Chemical Changes: In these changes, a substance undergoes a transformation that alters its chemical composition, forming new substances. For example, burning wood, rusting of iron, or digestion of food.
Biological Changes: These are changes related to living organisms, such as growth, reproduction, or aging. Examples include a seed sprouting into a plant or a caterpillar transforming into a butterfly.
A physical change involves a change in the state or appearance of a substance but does not affect its chemical identity. Common physical changes include:
Melting ice into water.
Dissolving sugar in water.
Crushing a can.
These changes are usually reversible.