NCERT Class 10 Science Chapter 1 Chemical Reactions and Equations

NCERT Class 10 Science Chapter 1 Chemical Reactions and Equations is where board chemistry begins: writing word-equations, balancing chemical equations, and recognising the types of reactions you will use for the next three years. This page gives you the official chapter PDF from the NCERT source, a page-wise topic map taken from the textbook itself, the chapter’s key equations, and an exercise-wise view of the in-text questions and end exercises — all from the textbook updated for the 2026-27 session.

Download the Official NCERT Class 10 Science Chapter 1 PDF

The verified download for this chapter is in the official PDF table on this page. The link points to the file hosted on the official NCERT website, is checked before listing, and needs no sign-up. Keep the PDF saved offline — the page numbers in the topic map below match the official file exactly, so you can jump straight to any activity or section.

What You Study in Chemical Reactions and Equations

The chapter has three teaching sections built around eleven hands-on activities. Section 1.1 (Chemical Equations) starts from a word-equation — reactants on the left, products on the right — and teaches you to write a skeletal chemical equation and then balance it, because mass is conserved: atoms are neither created nor destroyed in a chemical reaction, so the number of atoms of each element must be the same on both sides. You also learn to make an equation more informative with physical-state symbols, where (aq) means the substance is a solution in water.

Section 1.2 (Types of Chemical Reactions) classifies reactions as combination, decomposition, displacement, double displacement, and oxidation-reduction. Section 1.3 brings the chemistry into everyday life through corrosion and rancidity — both effects of oxidation. The chapter closes with the official summary and the end exercises.

Topic-Wise Index and Page Map of Chemical Reactions and Equations

Section-wise index of Chemical Reactions and Equations with the official NCERT page numbers (from the NCERT textbook):

Key Definitions and Terms in Chemical Reactions and Equations

• Word-equation — a chemical reaction written in words, with the reactants on the left-hand side and the products on the right.
• Reactants and products — reactants are the substances that undergo chemical change; products are the new substances formed.
• Skeletal chemical equation — an unbalanced equation in which the number of atoms of each element is not yet the same on both sides.
• Balanced chemical equation — an equation with the number of atoms of each element equal on both sides, as the law of conservation of mass requires.
• Exothermic reaction — a reaction that releases a large amount of heat along with the formation of products.
• Precipitation reaction — any reaction that produces an insoluble substance, called a precipitate.
• Oxidation — the gain of oxygen or loss of hydrogen by a substance during a reaction.
• Reduction — the loss of oxygen or gain of hydrogen by a substance during a reaction.

Important Formulas, Equations and Diagrams in Chemical Reactions and Equations

This chapter’s marks come from writing and balancing equations correctly, then naming the reaction type. One canonical equation per type, exactly as the textbook develops them:

• Combination: \(CaO + H_2O \rightarrow Ca(OH)_2\) — quick lime and water combine into a single product, slaked lime, releasing heat (an exothermic reaction).
• Decomposition: a single reactant breaks into simpler products; heating ferrous sulphate is the textbook’s thermal decomposition example.
• Displacement: \(Fe + CuSO_4 \rightarrow FeSO_4 + Cu\) — iron displaces copper from copper sulphate solution.
• Double displacement: \(Na_2SO_4 + BaCl_2 \rightarrow BaSO_4 + 2NaCl\) — ions exchange between the reactants and the insoluble barium sulphate precipitate forms.
• Oxidation-reduction: \(CuO + H_2 \rightarrow Cu + H_2O\) — copper oxide is reduced while hydrogen is oxidised, both in the same reaction.

Add the state symbols (s), (l), (g) and (aq) once an equation balances — the examiner reads them as part of a complete answer. The diagrams to practise are the activity set-ups the equations come from, especially the burning magnesium ribbon and the electrolysis of water.

In-Text and Exercise Questions in Chemical Reactions and Equations

Question practice in this chapter comes in two layers:

• In-text question sets (3) — short checks placed after Sections 1.1, 1.2.2 and 1.3, testing equation-writing and reaction types immediately after you learn them.
• End exercises (20 questions) — an exercise-wise mix: option-based questions on reaction types, balancing practice, writing equations from word descriptions, classifying reactions with reasons, and short explanations of corrosion and rancidity.

The eleven activities (1.1 to 1.11) are not optional extras — exercise answers routinely lean on what the activities showed, so read each activity’s observation before you attempt the related question.

How to Prepare Chemical Reactions and Equations for the Board Exam

1. Read Sections 1.1 to 1.3 in the official PDF in order, doing each activity’s observation mentally as you go.
2. Practise balancing five equations a day using the hit-and-trial method the textbook teaches — start from the skeletal equation, never change a formula to force a balance.
3. Make a one-page table of the five reaction types, each with its textbook example equation.
4. Answer the three in-text question sets the same day you read their sections, then work the 20 end-exercise questions across your revision week.
5. Finish with the official summary on this page, and confirm the current chapter weightage from the CBSE syllabus for the 2026-27 session on the official CBSE website before you plan revision time.

Common Mistakes Students Make in Chemical Reactions and Equations

These are the errors that actually cost marks in this chapter — most study pages will not tell you this plainly:

• Changing a chemical formula to balance an equation — you may only adjust the coefficients; altering a formula creates a different substance and loses the mark.
• Leaving an equation skeletal — an unbalanced equation contradicts the conservation of mass and is treated as incomplete.
• Dropping the state symbols after balancing, when the question asks for a complete equation.
• Labelling oxidation and reduction on the wrong substances — track oxygen gained or hydrogen lost for each reactant separately.
• Writing corrosion and rancidity as unrelated definitions — the examiner expects you to connect both to oxidation, as the chapter does.

How to Use NCERT Solutions for This Chapter

When you practise the chapter exercises, keep the official PDF open and check that every solved step follows the definitions, equations, activities, or examples in the textbook. Do not memorise only the final answer; in balancing and classification questions, the reason written beside each step is what earns marks.

Official NCERT Summary of Chemical Reactions and Equations

– A complete chemical equation represents the reactants, products and their physical states symbolically. – A chemical equation is balanced so that the numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation. Equations must always be balanced. – In a combination reaction two or more substances combine to form a new single substance. – Decomposition reactions are opposite to combination reactions. In a decomposition reaction, a single substance decomposes to give two or more substances. – Reactions in which heat is given out along with the products are called exothermic reactions. – Reactions in which energy is absorbed are known as endothermic reactions. – When an element displaces another element from its compound, a displacement reaction occurs. – Two different atoms or groups of atoms (ions) are exchanged in double displacement reactions. – Precipitation reactions produce insoluble salts. – Reactions also involve the gain or loss of oxygen or hydrogen by substances. Oxidation is the gain of oxygen or loss of hydrogen. Reduction is the loss of oxygen or gain of hydrogen.

Source: NCERT official textbook (Class 10 science).

Frequently Asked Questions

Related study material

• NCERT Class 10 Science book
• Chapter 2: Acids, Bases and Salts
• Chapter 3: Metals and Non-metals
• Experiments And Activities
• Formulas And Equations
• Important Questions
• Notes
• Previous Year Questions
• Glossary And Keywords