NCERT Class 10 Science Science: Chapter 1 — Chemical Reactions and Equations
This chapter, 'Chemical Reactions and Equations,' from NCERT Class 10 Science, introduces students to the fundamental concepts of chemical changes and reactions. It begins by presenting everyday situations like milk souring or food cooking, prompting students to identify the changes occurring. Through activities, students learn to recognize indicators of a chemical reaction, such as changes in state, color, evolution of gas, or temperature. The chapter explains how to represent these reactions using word equations, identifying reactants and products. It emphasizes that chemical reactions involve the transformation of substances, leading to new products. This foundational understanding is crucial for further study in chemistry and helps students analyze and describe chemical processes observed in daily life.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 10 |
| Subject | Science |
| Book | Science |
| Chapter | Chapter 1 — Chemical Reactions and Equations |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 656 |
Learning outcomes
- Identify situations where chemical reactions occur.
- Recognize indicators of a chemical reaction (change in state, color, gas evolution, temperature change).
- Understand the terms reactants and products.
- Represent simple chemical reactions using word equations.
Vocabulary
| Word | Meaning |
|---|---|
| Reactants | Substances that undergo a chemical change in a reaction. |
| Products | New substances formed during a chemical reaction. |
| Chemical reaction | A process that leads to the transformation of one set of chemical substances to another. |
| Word-equation | A representation of a chemical reaction using words to show reactants and products. |
| Fermented | Undergo fermentation; a chemical process that converts carbohydrates into alcohol or organic acids. |
| Respire | Breathe; the process of taking in oxygen and giving out carbon dioxide. |
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Practice questions
- List four observations that help us determine if a chemical reaction has taken place. Answer: Change in state, change in colour, evolution of a gas, and change in temperature.
- What are reactants and products in a chemical reaction? Answer: Reactants are the substances that undergo a chemical change, and products are the new substances formed.
- Write the word-equation for the reaction where hydrogen reacts with oxygen to form water. Answer: Hydrogen + Oxygen → Water
Frequently asked questions
What is the main topic of NCERT Class 10 Science Chapter 1?
NCERT Class 10 Science Chapter 1 deals with Chemical Reactions and Equations.
What are the signs that a chemical reaction has occurred?
Signs include a change in state, change in colour, evolution of a gas, or a change in temperature.
How can a chemical reaction be represented in a simple form?
A simple form is a word-equation, showing reactants and products.
What are reactants in a chemical reaction?
Reactants are the substances that undergo a chemical change.
What are products in a chemical reaction?
Products are the new substances formed as a result of the reaction.
What is the purpose of the arrow in a word-equation?
The arrow points towards the products and shows the direction of the reaction.
Related resources
Important topics
Topics covered
NCERT Class 10 Science — Science — Chapter 1 — Chemical Reactions and Equations. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.