Every day, we notice a variety of changes taking place around us. Change is an unavoidable occurrence. It happens all the time and everywhere. Changes, on the other hand, differ in a number of ways. Some changes are rapid, while others are gradual. Some are temporary, while others are permanent.
Some changes are periodic, while others are not. Some are natural, while others are artificial. Some are reversible, while others are not. On a broader level, a change can be classified as chemical or physical depending on how the properties of a subject change when it undergoes the change.
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Definition: A substance is said to change physically when only its physical properties, such as shape, size, colour, state, or appearance, change. Its chemical composition is unaffected. Physical changes have the following characteristics:
Folding a paper sheet, melting wax, freezing and boiling water, melting ice, condensation, vaporisation, and dissolving sugar in water are examples of physical changes. |
Physical Change in Chemistry Questions with Solutions
Q1. Size, shape, colour, and state of a substance are examples of ________ properties.
a.) chemical
b.) physical
c.) electrical
d.) all of the above
Correct Answer – (b.) physical.
Q2. A physical change is generally _________.
a.) reversible
b.) irreversible
c.) both reversible and irreversible
d.) none of the above
Correct Answer – (a.) reversible.
Q3. During a physical change, a substance undergoes a change in its _________.
a.) physical properties
b.) chemical properties
c.) both (a) and (b)
d.) none of the above
Correct Answer – (a.) physical properties.
Q4. Which of the following is not an example of physical change?
a.) evaporation
b.) condensation
c.) boiling
d.) rusting
Correct Answer – (d.) rusting.
Q5. Which of the following is an example of physical change?
a.) burning of paper
b.) ripening of fruit
c.) cutting of wood
d.) cooking food
Correct Answer – (c.) cutting of wood.
Q6. Define physical changes.
Answer: A physical change is one in which a substance’s physical properties, such as shape, size, colour and state, change.
Physical changes are usually reversible (with some exceptions). There is no new substance formed as a result of this change.
An ice cube melting into water is an example of physical change.
Q7. How can you say that crystallisation is not a chemical change?
Answer: Even if the crystal has different properties than other solids, crystallising it does not result in the formation of a new molecule. A chemical reaction does not occur when graphite is transformed into a diamond. Crystallisation is, thus, considered a physical change.
Q8. Can all physical changes be reversed?
Answer: No, all physical changes are not reversible.
Irreversible physical changes include cutting grass or pulverising a rock. Since the pieces of wood cannot be put back together to form the tree, chopping wood for a fire represents an irreversible physical change.
Q9. Give an example of a physical change caused by the action of heat.
Answer: The physical change of ice melting to form water is caused by the action of heat.
Q10. What changes may happen in physical change?
Answer: A physical change occurs when a substance undergoes a change in its physical properties, such as shape, size, colour, state, or appearance. Physical changes are generally reversible in nature. The chemical composition remains unchanged during these physical changes, and no new substance is formed.
Q11. Differentiate between physical and chemical changes.
Answer: The difference between physical and chemical changes are as follows:
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Physical Change |
Chemical Change |
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When a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged. |
When a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances. |
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Physical change is a temporary change. |
A chemical change is a permanent change. |
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A physical change affects only physical properties, i.e. shape, size, etc. |
Chemical changes are both physical and chemical properties of the substance, including its composition. |
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Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. |
A few examples of chemical change are digestion of food, burning of coal, rusting, etc. |
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Physical change is easily reversible, i.e. original substance can be recovered. |
Chemical changes are irreversible, i.e. original substance cannot be recovered. |
Q12. What are the characteristics of physical change?
Answer: A physical change is characterised by a change in physical properties. Melting, transition to a gas, change in strength, change in durability, changes in crystal form, textural change, shape, size, colour, volume, and density are all examples of physical properties.
Q13. Give some examples of physical changes.
Answer: Some examples of physical changes are:
- Melting an ice cube
- Boiling water
- Mixing sand and water
- Breaking a glass
- Dissolving sugar and water
- Sublimation of dry ice
- Crumpling a paper bag
Q14. Is the formation of alloy a physical change?
Answer: Alloying is the process of combining different metal elements. Brass is a copper and zinc alloy. Separating individual metals from an alloy can be difficult and may require chemical processing. Creating an alloy is an example of a physical change that cannot be easily reversed.
Q15. Are solutions or mixtures a physical or chemical change?
Answer: When you mix the materials together, it can be difficult to tell whether or not a chemical reaction has occurred. If no colour change, temperature change, precipitate formation, or gas production occurs, the solution is usually a physical change. Otherwise, a chemical reaction has occurred, resulting in a chemical change.
Practice Questions on Physical Change
Q1. Which of the following is not a characteristic of a physical change?
a.) shape
b.) colour
c.) size
d.) new substance
Q2. Which property remains constant even after physical and chemical changes?
a.) density
b.) shape
c.) mass
d.) arrangement of particles
Q3. What is the change called if there is a change in physical state only?
Q4. What kind of change is dissolving?
Q5. How to identify a physical change?
Click the PDF to check the answers for Practice Questions.
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