Detailed NCERT Solutions for Class 10 Science Chapter 1 with Explanations

NCERT Solutions for Class 10 Science Chapter 1 provide detailed explanations, step-by-step answers, and free PDF downloads to help students excel in their exams.

Q: What is a chemical reaction?
A chemical reaction is a process in which one or more substances (reactants) undergo a change to form one or more new substances (products) with different properties.

Q: What are the characteristics of a chemical reaction?
A chemical reaction is usually identified by changes such as the release of gas, change in color, formation of precipitate, change in temperature, and emission of light or sound.

Q: Define a balanced chemical equation.
A balanced chemical equation is one in which the number of atoms of each element is equal on both the reactant and product sides, following the law of conservation of mass.

Q: Why should a chemical equation be balanced?
A chemical equation should be balanced to follow the law of conservation of mass, which states that mass cannot be created or destroyed in a chemical reaction.

Q: What is a combination reaction? Give an example.
A combination reaction is a reaction where two or more substances combine to form a single product. Example: When magnesium burns in oxygen, it forms magnesium oxide.

Q: What is a decomposition reaction? Give an example.
A decomposition reaction is a type of chemical reaction where a single compound breaks down into two or more simpler substances. Example: Heating calcium carbonate forms calcium oxide and carbon dioxide.

Q: What is a displacement reaction? Give an example.
A displacement reaction is a reaction in which a more reactive element replaces a less reactive element from its compound. Example: When iron reacts with copper sulfate, it forms iron sulfate and copper.

Q: What is a double displacement reaction?
A double displacement reaction occurs when the ions of two compounds exchange to form new compounds. Example: The reaction of barium chloride and sodium sulfate forms barium sulfate and sodium chloride.

Q: What is oxidation?
Oxidation is a chemical process in which a substance gains oxygen or loses hydrogen.

Q: What is reduction?
Reduction is the process in which a substance loses oxygen or gains hydrogen.

Q: What is redox reaction?
A redox reaction is a reaction in which both oxidation and reduction occur simultaneously.

Q: What happens when magnesium ribbon is burnt in air?
Magnesium reacts with oxygen in the air to form magnesium oxide, which appears as a white powder.

Q: What is rusting of iron?
Rusting of iron is a slow chemical reaction in which iron reacts with water and oxygen to form iron oxide, commonly known as rust.

Q: What is the role of a catalyst in a chemical reaction?
A catalyst is a substance that speeds up a chemical reaction without undergoing any permanent chemical change itself.

Q: How does baking soda help in extinguishing fire?
Baking soda releases carbon dioxide when heated, which helps to smother the fire by cutting off the oxygen supply.

Q: Why is respiration considered a chemical reaction?
Respiration is considered a chemical reaction because glucose reacts with oxygen to produce energy, carbon dioxide, and water.

Q: Why do apples turn brown when cut?
Apples turn brown due to oxidation, where the enzymes in the apple react with oxygen in the air.

Q: What is meant by exothermic and endothermic reactions?
Exothermic reactions release heat, while endothermic reactions absorb heat during the reaction.

Q: Give an example of an exothermic reaction.
The combustion of fuels like wood and coal is an example of an exothermic reaction.

Q: Give an example of an endothermic reaction.
The process of photosynthesis is an example of an endothermic reaction.

Q: What is the difference between physical and chemical changes?
A physical change does not form a new substance and is usually reversible, whereas a chemical change results in the formation of a new substance and is generally irreversible.

Q: What is meant by the term ‘precipitation reaction’?
A precipitation reaction is a reaction in which an insoluble solid, called a precipitate, forms in a solution.

Q: What is the significance of the law of conservation of mass?
The law of conservation of mass states that the total mass of reactants before a reaction is equal to the total mass of products after the reaction.

Q: What happens when a piece of sodium is placed in water?
Sodium reacts vigorously with water to form sodium hydroxide and releases hydrogen gas with heat.

Q: What happens when silver chloride is exposed to sunlight?
Silver chloride turns grey in sunlight due to its decomposition into silver and chlorine.

Q: What is the difference between oxidation and corrosion?
Oxidation is a general chemical reaction where a substance gains oxygen, while corrosion specifically refers to the slow destruction of metals due to oxidation and environmental factors.

Q: What is the importance of redox reactions in daily life?
Redox reactions are important in processes such as respiration, combustion, photosynthesis, and the corrosion of metals.

Q: Why do oil and fat-containing food items become rancid?
Oil and fat-containing food items become rancid due to oxidation, leading to a foul smell and bad taste.

Q: How can rancidity be prevented?
Rancidity can be prevented by storing food in airtight containers, adding antioxidants, or keeping them in refrigerators.

Q: Why is electrolysis used in metal extraction?
Electrolysis is used to extract metals from their ores by breaking down the compounds using electricity.

Q: Why are catalysts used in industries?
Catalysts speed up industrial chemical reactions, making them more efficient and cost-effective.

Q: What happens when iron nails are placed in copper sulfate solution?
Iron displaces copper from copper sulfate solution, forming iron sulfate and depositing copper.

Q: Why is lime water used to test carbon dioxide?
Lime water turns milky when carbon dioxide is passed through it, confirming its presence.

Q: What happens when lead nitrate is heated?
Lead nitrate decomposes to form lead oxide, nitrogen dioxide, and oxygen gas.

Q: What is the reaction when zinc reacts with dilute sulfuric acid?
Zinc reacts with sulfuric acid to produce zinc sulfate and hydrogen gas.

Q: Why do fireflies glow at night?
Fireflies glow due to a chemical reaction called bioluminescence, where a light-producing enzyme reacts with oxygen.

Q: Why is gold resistant to corrosion?
Gold is resistant to corrosion because it does not react with oxygen and moisture easily.

Q: Why does hydrogen gas not support combustion?
Hydrogen gas does not support combustion because it does not provide oxygen, which is essential for burning.

Q: What is meant by electrolytic decomposition?
Electrolytic decomposition is a reaction where an electric current breaks down a compound into its components.

Q: Why does vinegar react with baking soda?
Vinegar reacts with baking soda to release carbon dioxide gas due to an acid-base reaction.

Q: Why does a candle extinguish when covered with a glass?
A candle extinguishes when covered because the supply of oxygen is cut off.

Q: Why does iron lose its shine over time?
Iron loses its shine due to oxidation, leading to the formation of rust.

Q: Why is silver used in making mirrors?
Silver is highly reflective and does not corrode easily, making it ideal for mirrors.

Q: What is meant by the thermite reaction?
The thermite reaction is a highly exothermic reaction used to weld railway tracks, involving aluminum and iron oxide.

Q: What happens when quicklime is mixed with water?
Quicklime reacts with water to form slaked lime, releasing heat in an exothermic reaction.

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NCERT Exemplar Science for Class 10 – NCERT Publication

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NCERT Solutions for Class 10 Science Chapter 1 – A Complete Guide

NCERT Solutions for Class 10 Science Chapter 1, Chemical Reactions and Equations, serve as a crucial resource for students preparing for board exams. This chapter lays the foundation for understanding different types of chemical reactions and their significance in real life. With expert-recommended study materials, students can master concepts, practice questions, and develop a problem-solving approach essential for exams.

Understanding Chemical Reactions and Equations

Chemical reactions occur when substances interact to form new products. This chapter explains how chemical changes take place, what factors influence reactions, and how to represent them using chemical equations. Balanced chemical equations are a major focus, helping students understand the conservation of mass principle.

The chapter introduces different types of chemical reactions, including combination, decomposition, displacement, and redox reactions. Real-life examples, such as rusting of iron and food spoilage, make the learning process engaging. Understanding these reactions builds a strong conceptual base for further chemistry studies.

Why NCERT Solutions are Essential?

NCERT solutions offer structured, step-by-step answers to textbook questions, ensuring that students grasp the fundamentals effectively. These solutions are written in simple language and follow the CBSE board’s marking scheme. By practicing these solutions, students can learn how to write accurate answers for board exams.

NCERT solutions also include reasoning-based questions, fill-in-the-blanks, match-the-following, and HOTS (Higher Order Thinking Skills) to develop analytical thinking. Since most board exam questions are derived from NCERT textbooks, solving these exercises significantly boosts confidence.

Types of Questions Covered in NCERT Solutions

The solutions in this chapter include:

• Textbook Exercise Solutions – Covers all in-text and end-text questions with accurate explanations.
• Conceptual Questions – Tests understanding of different types of chemical reactions and their applications.
• Equation-Based Problems – Helps students practice balancing chemical equations efficiently.
• Practical-Based Questions – Focuses on lab-based experiments related to decomposition and displacement reactions.
• Assertion & Reason Questions – Develops analytical skills by testing logical reasoning abilities.

Expert Tips for Studying Chapter 1 Effectively

1. Understand the Types of Chemical Reactions – Learn the characteristics and examples of combination, decomposition, displacement, and redox reactions.
2. Master Balancing Equations – Practice balancing different chemical equations to reinforce the conservation of mass.
3. Use Diagrams & Flowcharts – Visual aids help in understanding reaction processes more effectively.
4. Practice NCERT Questions Regularly – Solve in-text, back exercises, and exemplar problems for complete revision.
5. Solve Sample Papers & Mock Tests – Practicing previous years’ board questions helps in understanding the exam pattern.

Common Mistakes to Avoid

• Writing unbalanced chemical equations without checking atom counts.
• Confusing oxidation and reduction reactions.
• Not understanding the difference between physical and chemical changes.
• Ignoring practical-based questions which are essential for exams.
• Memorizing equations without understanding the reaction mechanisms.

NCERT solutions not only help in board exam preparation but also build a strong foundation for competitive exams like NEET and JEE. With a clear study strategy, consistent practice, and expert-recommended books, mastering Chemical Reactions and Equations becomes much easier.