---
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entity_type: "chapter"
id: "69bff482fb5daab696d9ec22"
title: "Changes Around Us: Physical and Chemical"
board: "CBSE"
curriculum: "CBSE"
class: "Class 7"
subject: "Science"
book: "Curiosity"
chapter: "Changes Around Us: Physical and Chemical"
chapter_slug: "changes-around-us-physical-and-chemical"
canonical_url: "https://www.edzy.ai/cbse-class-7-science-curiosity-changes-around-us-physical-and-chemical"
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source: "Edzy"
version: 1
last_updated: "2026-06-20"
---

# Changes Around Us: Physical and Chemical

This chapter discusses the concept of various changes that occur around us, classifying them into physical and chemical changes, alongside their implications and examples.

---

## Knowledge Snapshot

| Field | Details |
| :--- | :--- |
| Class | Class 7 |
| Subject | Science |
| Book | Curiosity |
| Chapter | Changes Around Us: Physical and Chemical |
| Pages | 57-72 |

---

## Chapter Summary

### Short Summary
This chapter explains the different kinds of changes in substances around us, emphasizing their classifications into physical and chemical changes.

### Detailed Summary
The chapter elaborates on various changes observed in daily life, labeling them as physical or chemical. Physical changes only affect the appearance of substances without forming new substances, while chemical changes result in the formation of new substances through reactions, demonstrated through various experiments and examples such as rusting and combustion. The conditions necessary for combustion and other changes that can or cannot be reversed are discussed, emphasizing the everyday relevance and natural implications of these processes.

---

## Topic-Wise Explanation

### A Substance May Change in Appearance but Remain the Same!
These are physical changes where substances may change form (like in melting or crushing) but do not create new substances.

### A Substance May Change in Appearance and Not Remain the Same!
Chemical changes occur when new substances are formed, such as through chemical reactions like the interaction of lime water and carbon dioxide.

### Rusting
Rusting of iron is a chemical change resulting in the formation of rust (iron oxide).

### Combustion
The process of combustion involves burning substances to produce heat and light, along with new products such as magnesium oxide from magnesium and oxygen.

### Can Physical and Chemical Changes Occur in the Same Process?
An example is the burning of a candle where both physical (melting wax) and chemical (burning wax) changes occur simultaneously.

### Are Changes Permanent?
Some changes, like melting ice, can be reversed, while others, like chopping vegetables, cannot.

### Are All Changes Desirable?
Changes can be classified as desirable (like curdling milk) or undesirable (like rusting), depending on the context.

### Some Slow Natural Changes
Natural processes like weathering and erosion reflect gradual changes in the environment that comprise physical and chemical changes together.

---

## Core Ideas

| Idea | Explanation |
| :--- | :--- |
| Physical Change | A change in physical properties without forming new substances. |
| Chemical Change | A change that forms new substances through chemical reactions. |

---

## Key Concepts

| Concept | Meaning |
| :--- | :--- |
| Ignition Temperature | The minimum temperature at which a substance catches fire. |
| Combustible Substances | Materials that can undergo combustion. |

---

## Important Points for Revision

* Physical changes do not create new substances.
* Chemical changes result in new substances.
* Some changes can be reversed while others cannot.
* Examples of physical changes include melting and boiling.
* Examples of chemical changes include rusting and combustion.
* Oxygen is essential for combustion.
* Weathering leads to soil formation through physical and chemical processes.
* Not all changes are desirable; some are beneficial while others are harmful.
* Changes can be categorized based on their permanency.
* The study of candle burning illustrates both physical and chemical changes.

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## Practice Questions

### Short Answer Questions
1. Define a physical change with an example.
2. What happens during rusting?
3. Explain what combustion is.
4. Provide an example of a change that can't be reversed.
5. What is ignition temperature?

### Long Answer Questions
1. Discuss the differences between physical and chemical changes with examples from the chapter.
2. Explain the process of rusting and why it is considered a chemical change.
3. Describe the experiments that demonstrate chemical changes and what conclusions can be drawn from them.

---

## Related Concepts

* Chemical Reactions
* Carbon Dioxide Test
* Properties of Substances

---

## Source Attribution

| Field | Value |
| :--- | :--- |
| Source | Edzy |
| Reference Type | examSubjectBookChapter |
| Reference ID | 69bff482fb5daab696d9ec22 |
| Canonical URL | https://www.edzy.ai/cbse-class-7-science-curiosity-changes-around-us-physical-and-chemical |
| Markdown URL | https://www.edzy.ai/okf/chapter/cbse-class-7-science-curiosity-changes-around-us-physical-and-chemical.md |