Skip to main content

Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 2 - Physical and Chemical Changes 😊




Exercise
Question 1.
Define:
(a) a physical change, (b) a chemical change.
Answer:
(a) Physical Change: A physical change is a temporary change in which no new substance is formed and the chemical composition of the original substance remains the same, even though its physical properties like colour, state, shape, size etc. might change.
(b) Chemical Change: A chemical change is permanent change in which new substances are formed whose chemical composition and physical and chemical properties are different from those of in original substance.

Question 2.
Classify the following as a physical or a chemical change.
(a) Drying of wet clothes
(b) Manufacture of salt from sea water
(c) Butter getting rancid
(d) Boiling of water
(e) Burning of paper
(f) Melting of wax
(g) Burning of coal
(h) Formation of clouds
(i) Making of a sugar solution
(j) Glowing of an electric bulb
(k) Curdling of milk
Answer:
Physical change
(a) Drying of wet clothes
(b) Manufacture of salt from sea water
(d) Boiling of water
(f) Melting of wax
(h) Formation of clouds
(i) Making of a sugar solution
(j) Glowing of an electric bulb.
Chemical change
(c) Butter getting rancid
(e) Burning of paper
(g) Burning of coal
(k) Curdling of milk

Question 3.
Fill in the blanks.
Answer:
(a) The process of a liquid changing into a solid is called freezing.
(b) A change, which alters the composition of a substances, is known as a chemical change.
(c) There is no change in the composition of the substance during a physical change.
(d) The reaction in which energy is evolved is called exothermic reaction.

Question 4.
Given reason:
(a) Freezing of water to ice and evaporation of water are physical changes.
(b) Burning of a candle is both a physical and chemical change.
(e) Burning of paper is a chemical change.
(d) Cutting of a cloth piece is a physical change, though it cannot be reversed.
Answer:
(a) Freezing of water to ice and evaporation of water are physical change because water can be brought back to its original (liquid) form by

  1. We can heat the ice to bring it back to water.
  2. We can cool down the vapours to bring it back to water.

(b) When a candle is lighted, some of the solid wax first melts and turns into liquid, then it turns into vapours to produce a flame. New substances CO2and H2O vapours are formed along-with the evolution of light and heat energy. This shows a chemical change. When some of the molten wax drops to the floor, it again solidifies. Which shows a physical change. Thus the melting of candle wax is a physical change and the production of CO2 and H2O represents chemical change.

(c) When a piece of paper is burnt a new substance ash is produced. Even when the burning is stopped, the ash cannot be changed back into paper. This shows that the formation of the ash from paper is a permanent and irreversible change.

(d) Because it does not change chemical composition of cloth and the change is only in the state, size, shape, colour, texture or the smell of some or all of the substances that undergo physical change.

Question 5.
Give four difference between physical and chemical changes.
Answer:
The differences are Physical and Chemical Changes:
Physical change

  1. In a physical change no new substance is formed and the chemical composition of substance remains same. There are changes only in physical properties and state.
  2. Temporary change which can be reversed by simple physical methods.
  3. Weight of original substance doesn’t change
  4. Energy like heat, light etc. may or may not be absorbed or released

Chemical change

  1. In a chemical change new substance with entirely different chemical composition and properties is formed.
  2. Permanent change and irreversible
  3. Weight of original substances may increase or decrease
  4. Energy like heat, light etc. are given out or absorbed.


Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 2 - Physical and Chemical Changes 😊

Popular posts from this blog

ICSE Solutions for Class 9 History and Civics | Indian History World Developments and Civics ICSE Class IX Question Answers Total Solutions APC Avichal Publishing Company BB Tayal

📚  ICSE Solutions for Class 9 History and Civics ICSE Solutions for Class 9 History and Civics Indian History, World Developments and Civics for ICSE Class- IX by BB-Tayal of Avichal Publishing Company (APC) Buy ICSE Total History & Civics For Class 9 (Latest Syllabus 2022 ) Online Icse Total History & Civics For Class 9 (Latest Syllabus 2022) HISTORY The Harappan Civilization Early Vedic Civilization The Later Vedic Age India in the 6th Century BC: Rise of Jainism and Buddhism The Mauryan Empire The Sangam Age: Kingdoms and The Social and Economic Conditions The Age of the Guptas South India and the Cholas The Delhi Sultanate The Mughal Empire The Composite Culture: Bhakti Movement, Sufism and Influence of Christianity on Indian Society The Renaissance The Reformation Industrial Revolution and Capitalism and Socialism CIVICS Our Constitution and Its Preamble Fundamental Rights, Fundamental Duties and Dir

ICSE Solutions for Class 9 History and Civics - The Harappan Civilization

ICSE Solutions for Class 9 History and Civics – The Harappan Civilization ICSE Solutions for Class 9 History and Civics – The Harappan Civilization Exercises Question 1. Mention any two sources to reconstruct the Harappan Civilization. Answer: The remains of the two towns, Mohenjo-daro and Harappan reveal and remarkable sense of town planning—the drainage system, the Great Bath, the Assembly Hall and other public buildings. From Seals we come to know about the physical features, dress, ornaments and religious beliefs of the people. Question 2. Why did the Indus Valley Civilization come to be known as Harappan Civilization? Answer: Indus Valley Civilization came to be known as Harappan Civilization because this Civilization flourished in the pre-historic cities of Harappan in West Punjab and Mohenjo-daro in Sind. Question 3. Mention any two important centres of the Indus Valley Civilization. Answer: Northern and Western parts of India and the present day Pakistan.

ICSE Solutions for Class 8 History and Civics - A Period of Transition

ICSE Solutions for Class 8 History and Civics – A Period of Transition I. FILL IN THE BLANKS:   1. The Renaissance thinkers believed in life in this World.   2. The term Reformation refers to two major developments, the Protestant Reformation and the Catholic Reformation.   3. Vasco-da-Gama reached Calicut on the West Coast of India.   4. The Industrial Revolution began in England in about 1750 .   5. In 1793, Eli Whitney invented a Cotton gin . II. MATCH THE CONTENTS OF COLUMN A AND COLUMN B: Answer:   III. STATE WHETHER THE FOLLOWING STATEMENTS ARE TRUE OR FALSE: 1. The Renaissance and the Reformation along with new voyages ushered in the Modern Age. True. 2. The Industrial Revolution began in Germany.   False. 3. Me Adam devised railway tracks. False. 4. The Rise of capitalism and imperialism can be attributed to the industrial Revolution. True. 5. The East India Company gradually became rulers from being traders. True.