All Exams >
Class 8 >
Chemistry Class 8 ICSE >
All Questions
All questions of Physical and Chemical Changes for Class 8 Exam
What type of change is represented by the sublimation of camphor?- a)Physical change
- b)Irreversible change
- c)Chemical change
- d)Periodic change
Correct answer is option 'A'. Can you explain this answer?
What type of change is represented by the sublimation of camphor?
a)
Physical change
b)
Irreversible change
c)
Chemical change
d)
Periodic change
|
Sanskriti Sengupta answered |
Understanding Sublimation of Camphor
Sublimation is a fascinating process where a solid turns directly into a gas without passing through the liquid phase. The sublimation of camphor is a classic example of this physical change.
Characteristics of Physical Change
- No New Substance Formed: During sublimation, camphor changes from solid to gas, but its chemical composition remains the same. This means that the identity of the substance does not change.
- Reversible Process: The process can be reversed. When the gas cools down, it can condense back into a solid form of camphor. This reversibility is a key feature of physical changes.
- Energy Changes: Sublimation involves energy changes in the form of heat. Solid camphor absorbs energy from the environment, allowing it to transition to a gaseous state.
Why Not Chemical Change?
- No Chemical Reactions: A chemical change involves the breaking and forming of chemical bonds, resulting in new substances. Since camphor retains its properties and does not form new substances during sublimation, it is not considered a chemical change.
Conclusion
Therefore, the sublimation of camphor is classified as a physical change due to its reversible nature, the absence of new substances, and the preservation of the original chemical identity. Understanding these properties helps in distinguishing between physical and chemical changes in various substances.
Sublimation is a fascinating process where a solid turns directly into a gas without passing through the liquid phase. The sublimation of camphor is a classic example of this physical change.
Characteristics of Physical Change
- No New Substance Formed: During sublimation, camphor changes from solid to gas, but its chemical composition remains the same. This means that the identity of the substance does not change.
- Reversible Process: The process can be reversed. When the gas cools down, it can condense back into a solid form of camphor. This reversibility is a key feature of physical changes.
- Energy Changes: Sublimation involves energy changes in the form of heat. Solid camphor absorbs energy from the environment, allowing it to transition to a gaseous state.
Why Not Chemical Change?
- No Chemical Reactions: A chemical change involves the breaking and forming of chemical bonds, resulting in new substances. Since camphor retains its properties and does not form new substances during sublimation, it is not considered a chemical change.
Conclusion
Therefore, the sublimation of camphor is classified as a physical change due to its reversible nature, the absence of new substances, and the preservation of the original chemical identity. Understanding these properties helps in distinguishing between physical and chemical changes in various substances.
What is the main difference between physical and chemical changes?- a)Chemical changes produce new substances while physical changes do not.
- b)Physical changes are slower than chemical changes.
- c)Physical changes are always reversible.
- d)Chemical changes occur naturally, while physical changes are man-made.
Correct answer is option 'A'. Can you explain this answer?
What is the main difference between physical and chemical changes?
a)
Chemical changes produce new substances while physical changes do not.
b)
Physical changes are slower than chemical changes.
c)
Physical changes are always reversible.
d)
Chemical changes occur naturally, while physical changes are man-made.
|
Foothill Academy answered |
The main difference is that chemical changes produce new substances with different properties, while physical changes do not alter the original substance's composition and often allow for the original material to be recovered.
Which of the following is an example of a fast change?- a)Milk turning into curd
- b)Rusting of iron
- c)A child growing
- d)Breaking a glass
Correct answer is option 'D'. Can you explain this answer?
Which of the following is an example of a fast change?
a)
Milk turning into curd
b)
Rusting of iron
c)
A child growing
d)
Breaking a glass
|
|
Foothill Academy answered |
Breaking a glass occurs very quickly and is considered a fast change. In contrast, processes like rusting and growth take much longer to happen, while the curdling of milk, although not immediate, is also relatively quicker than the other examples.
What happens during the process of fermentation?- a)A liquid freezes into a solid.
- b)A solid turns into a gas.
- c)Microorganisms convert food into different substances.
- d)A gas condenses into a liquid.
Correct answer is option 'C'. Can you explain this answer?
What happens during the process of fermentation?
a)
A liquid freezes into a solid.
b)
A solid turns into a gas.
c)
Microorganisms convert food into different substances.
d)
A gas condenses into a liquid.
|
|
Foothill Academy answered |
Fermentation is the process in which microorganisms, such as yeast or bacteria, convert sugars into different substances, often producing alcohol or acid. This process is a chemical change and results in new products that cannot revert to their original forms.
Which of the following describes a natural change?- a)Cooking food
- b)Making furniture
- c)Painting a wall
- d)The rotation of the Earth
Correct answer is option 'D'. Can you explain this answer?
Which of the following describes a natural change?
a)
Cooking food
b)
Making furniture
c)
Painting a wall
d)
The rotation of the Earth
|
|
Foothill Academy answered |
The rotation of the Earth is a natural change that occurs without human intervention, contributing to the cycle of day and night. In contrast, cooking food and making furniture are man-made changes.
Which of the following is a characteristic of a physical change?- a)A new substance is formed.
- b)The change can usually be reversed.
- c)The internal structure of the substance changes.
- d)The change is permanent.
Correct answer is option 'B'. Can you explain this answer?
Which of the following is a characteristic of a physical change?
a)
A new substance is formed.
b)
The change can usually be reversed.
c)
The internal structure of the substance changes.
d)
The change is permanent.
|
|
Foothill Academy answered |
Physical changes generally allow the material to return to its original state, meaning they are typically reversible. Examples include melting and boiling, where the original material can be recovered.
What type of change occurs when an ice cube melts into water?- a)Physical change
- b)Irreversible change
- c)Man-made change
- d)Chemical change
Correct answer is option 'A'. Can you explain this answer?
What type of change occurs when an ice cube melts into water?
a)
Physical change
b)
Irreversible change
c)
Man-made change
d)
Chemical change
|
|
Foothill Academy answered |
The melting of an ice cube is classified as a physical change because only the state of the matter changes from solid to liquid, and it can easily revert back to ice when cooled. This transformation does not produce any new substance.
What is a characteristic of periodic changes?- a)They happen randomly.
- b)They are always undesirable.
- c)They occur after the same interval of time.
- d)They cannot be predicted.
Correct answer is option 'C'. Can you explain this answer?
What is a characteristic of periodic changes?
a)
They happen randomly.
b)
They are always undesirable.
c)
They occur after the same interval of time.
d)
They cannot be predicted.
|
|
Foothill Academy answered |
Periodic changes are those that occur at regular intervals, such as the change of seasons or the rising and setting of the sun. This predictability is what defines them as periodic, distinguishing them from non-periodic changes.
Which of the following is an example of an irreversible change?- a)Melting butter
- b)Baking a cake
- c)Cutting paper
- d)Freezing water
Correct answer is option 'B'. Can you explain this answer?
Which of the following is an example of an irreversible change?
a)
Melting butter
b)
Baking a cake
c)
Cutting paper
d)
Freezing water
|
|
Foothill Academy answered |
Baking a cake is an irreversible change because once the ingredients are mixed and baked, they cannot be returned to their original states. This process creates new substances with different properties, unlike physical changes which can be reversed.
What defines a chemical change?- a)The internal composition of the substance changes.
- b)The change can be easily reversed.
- c)It involves only physical properties.
- d)No new substances are formed.
Correct answer is option 'A'. Can you explain this answer?
What defines a chemical change?
a)
The internal composition of the substance changes.
b)
The change can be easily reversed.
c)
It involves only physical properties.
d)
No new substances are formed.
|
|
Foothill Academy answered |
A chemical change is characterized by a transformation in the internal composition of a substance, resulting in new substances being formed. These changes are typically permanent and cannot be reversed easily.
Which of the following is a slow change?- a)Melting of ice
- b)Growth of a child
- c)Burning of paper
- d)Boiling of water
Correct answer is option 'B'. Can you explain this answer?
Which of the following is a slow change?
a)
Melting of ice
b)
Growth of a child
c)
Burning of paper
d)
Boiling of water
|
|
Foothill Academy answered |
The growth of a child is a slow change that occurs over many years, reflecting gradual physical and biological development. In contrast, the melting of ice, burning of paper, and boiling of water happen relatively quickly.
Which of the following describes an undesirable change?- a)Fruits ripening
- b)Boiling water
- c)Air pollution
- d)Digestion of food
Correct answer is option 'C'. Can you explain this answer?
Which of the following describes an undesirable change?
a)
Fruits ripening
b)
Boiling water
c)
Air pollution
d)
Digestion of food
|
|
Foothill Academy answered |
Air pollution is considered an undesirable change because it negatively affects health and the environment. In contrast, ripening fruits and digestion are beneficial processes, while boiling water is a neutral physical change.
Which of the following is an example of a periodic change?- a)A seed germinating
- b)The seasons changing
- c)A glass breaking
- d)Iron rusting
Correct answer is option 'B'. Can you explain this answer?
Which of the following is an example of a periodic change?
a)
A seed germinating
b)
The seasons changing
c)
A glass breaking
d)
Iron rusting
|
|
Foothill Academy answered |
The changing of seasons is a periodic change because it occurs at regular intervals throughout the year. This predictability distinguishes it from non-periodic changes, which do not follow a set schedule.
Which of the following processes is a physical change that can be reversed?- a)Baking bread
- b)Melting chocolate
- c)Rusting metal
- d)Burning wood
Correct answer is option 'B'. Can you explain this answer?
Which of the following processes is a physical change that can be reversed?
a)
Baking bread
b)
Melting chocolate
c)
Rusting metal
d)
Burning wood
|
|
Foothill Academy answered |
Melting chocolate is a physical change because it can be solidified again by cooling, thus reversing the process. In contrast, burning wood and baking bread are irreversible chemical changes.
What happens during the rusting of iron?- a)It occurs in a matter of seconds.
- b)It can be easily reversed.
- c)A new substance with different properties is formed.
- d)Iron changes color temporarily.
Correct answer is option 'C'. Can you explain this answer?
What happens during the rusting of iron?
a)
It occurs in a matter of seconds.
b)
It can be easily reversed.
c)
A new substance with different properties is formed.
d)
Iron changes color temporarily.
|
|
Foothill Academy answered |
Rusting is a chemical change that creates a new substance (rust) with different properties from iron. This process is irreversible, meaning the original metal cannot be restored without significant effort.
Chapter doubts & questions for Physical and Chemical Changes - Chemistry Class 8 ICSE 2025 is part of Class 8 exam preparation. The chapters have been prepared according to the Class 8 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 8 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
Chapter doubts & questions of Physical and Chemical Changes - Chemistry Class 8 ICSE in English & Hindi are available as part of Class 8 exam.
Download more important topics, notes, lectures and mock test series for Class 8 Exam by signing up for free.
Chemistry Class 8 ICSE
9 videos|51 docs|9 tests
|
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up
within 7 days!
within 7 days!
Takes less than 10 seconds to signup