NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations

NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations

Shivani PooniaUpdated on 17 Jul 2025, 03:49 PM IST

Do you know how milk turns sour, iron rusts and firecrackers explodes? Have you seen the transformation of milk into curd or conversion of water into ice? All these transformations discussed above are due to chemical reactions. You all might be thinking, what is a chemical reaction? What happens when a chemical reaction occurs? Chemical reaction is a process in which one or more substances react to form entirely new substances with different properties and composition. From burning of woods to digestion of food these chemical reactions occur everywhere around us. NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations helps students to understand all these interesting facts clearly.

This Story also Contains

  1. Download PDF of NCERT Solutions for Class 10 Science Chapter 1
  2. NCERT Solution For Class 10 Science Chapter 1 (Intext Questions)
  3. NCERT Solutions For Class 10 Science Chapter 1 (Exercise Questions with Answers)
  4. Practice Questions for Class 10 Science Chapter 1
  5. Approach to Solve Questions of Class 10 Science Chapter 1
  6. Topics and Subtopics Covered in the NCERT Textbook
  7. NCERT Class 10 Science Chapter 1: Important Reactions And E-book
  8. NCERT Solutions for Class 10 Science Chapter-Wise
  9. NCERT Solutions for Class 10
  10. NCERT Books and NCERT Syllabus
NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations
NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations

NCERT Solution for Class 10 Science of Chapter 1 gives clear, step-by-step answers for all chapters, aligned with the latest CBSE syllabus. These Solutions are drafted to simplify complex generalities and enhance your understanding. Class 10 Chemistry Chemical reactions focuses on writing and balancing chemical equations. These NCERT solutions follow the CBSE guidelines and give clear explanations, and also help students understand chemical processes and their types. NCERT Solutions for Class 10 serves as an important resource for mastering Chapter 1 Chemical Reactions and Equations and helps you to enhance performance in board exams.

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Download PDF of NCERT Solutions for Class 10 Science Chapter 1

To get NCERT Solutions for Class 10 Science Chemical Reactions and Equations PDF, click below on the download PDF icon. In this PDF, you will get detailed solutions to all the questions that are given in the NCERT textbook.

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NCERT Solution For Class 10 Science Chapter 1 (Intext Questions)

If you are looking for accurate and detailed answers to in text questions from NCERT Chapter 1 Chemical Reactions and Equations? These NCERT Solutions for Class 10 Science Chapter 1 provide step-by-step explanations to help students understand key concepts and improve exam performance.

Topic 1.1 Chemical equations: Page no-6

Q 1. Why should a magnesium ribbon be cleaned before burning in the air?

Answer:

Magnesium is a very reactive metal so it reacts with oxygen to form a layer of magnesium oxide on its surface.This layer is a stable oxide, so prevents further reaction of magnesium with oxygen. To remove this layer, a magnesium ribbon is cleaned using sandpaper before burning in air.

Q 2. (i) Write the balanced equation for the following chemical reactions.

Hydrogen + Chlorine → Hydrogen chloride

Answer:

The balanced equation for the following chemical reactions is given:

$\mathrm{H}_2(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g})$

Q 2. (ii) Write the balanced equation for the following chemical reactions.

Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride

Answer:

The balanced equation for the following chemical reactions is given:

$3 \mathrm{BaCl}_2(s)+\mathrm{Al}_2\left(\mathrm{SO}_4\right)_3(\mathrm{~g}) \rightarrow 3 \mathrm{BaSO}_4(\mathrm{~s})+2 \mathrm{AlCl}_3(\mathrm{~s})$

Q2. (iii) Write the balanced equation for the following chemical reactions.

Sodium + Water → Sodium hydroxide + Hydrogen

Answer:

The balanced equation for the following chemical reactions is given:

$2 \mathrm{Na}(s)+2 \mathrm{H}_2 \mathrm{O}(l) \rightarrow 2 \mathrm{NaOH}(a q)+\mathrm{H}_2(g)$

Q 3. (i) Write a balanced chemical equation with state symbols for the following reactions.

Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.

Answer:

The reaction solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride is given by :

$\mathrm{BaCl}_2(a q)+\mathrm{Na}_2 \mathrm{SO}_4(a q) \rightarrow \mathrm{BaSO}_4(s)+2 \mathrm{NaCl}(a q)$

Q 3. (ii) Write a balanced chemical equation with state symbols for the following reactions.

Sodium hydroxide solution (in water) reacts with a hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Answer:

The reaction of sodium hydroxide solution (in water) reacts with a hydrochloric acid solution (in water) to produce sodium chloride solution and water is given by :

$\mathrm{NaOH}(a q)+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{NaCl}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(l)$

Topic 1.2: Types of Chemical Reactions Page no- 10

Q 1. (i) A solution of a substance is used for whitewashing.

Name the substance ‘X’ and write its formula

Answer:

The substance ‘X’ is calcium oxide and its formula is CaO.

Q 1. (ii) A solution of a substance is used for whitewashing.

Write the reaction of the substance named in (i) above with water

Answer:

The reaction of calcium oxide with water is given by :

$\mathrm{CaO}(s)+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{Ca}(\mathrm{OH})_2$

Q 2. Why is the amount of gas collected in one of the test tubes in Activity double of the amount collected in the other? Name this gas.

Answer :

Water contains one part oxygen and two parts hydrogen. During electrolysis, oxygen and hydrogen are produced in a 1:2 ratio. In electrolysis, oxygen goes in one test tube and hydrogen in a second test tube, so the amount of gas collected in the second test tube is double of the first one.

Topic 1.3: Have you observed the effects of an oxidation reaction in everyday life? Page no-13

Q 1. Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Answer:

The colour of copper sulphate solution changes when an iron nail is dipped in it because iron displaces copper from copper sulphate forming iron sulphate, which is green.

$\mathrm{CuSO}_4(\mathrm{aq})+\mathrm{Fe}(s) \rightarrow \mathrm{FeSO}_4(\mathrm{aq})+\mathrm{Cu}(s)$

The colour changed from blue to green.

Q 2. Give an example of a double displacement reaction other than the one given in Activity.

Answer:

An example of a double displacement reaction other than the one given in Activity is :

$\mathrm{Na}_2 \mathrm{CO}_3(\mathrm{aq})+\mathrm{CaCl}_2(\mathrm{aq}) \rightarrow \mathrm{CaCO}_3(s)+2 \mathrm{NaCl}(a q)$

Q 3. (i) Identify the substances that are oxidized and the substances that are reduced in the following reactions.

$4 \mathrm{Na}(s)+\mathrm{O}_2 \rightarrow 2 \mathrm{Na}_2 \mathrm{O}(s)$

Answer:

$4 \mathrm{Na}(s)+\mathrm{O}_2 \rightarrow 2 \mathrm{Na}_2 \mathrm{O}(s)$

In the above reaction, Na is oxidised and oxygen gets reduced.

Q 3. (ii)Identify the substances that are oxidized and the substances that are reduced in the following reactions.

$\mathrm{CuO}(\mathrm{s})+\mathrm{H}_2(\mathrm{~g}) \rightarrow \mathrm{Cu}(\mathrm{s})+\mathrm{H}_2 \mathrm{O}(\mathrm{l})$

Answer:

$\mathrm{CuO}(s)+\mathrm{H}_2(g) \rightarrow \mathrm{Cu}(s)+\mathrm{H}_2 \mathrm{O}(l)$

In the above reaction, CuO is reduced to form Cu and hydrogen gets oxidized to water.

NCERT Solutions For Class 10 Science Chapter 1 (Exercise Questions with Answers)

Get comprehensive and well-structured answers to all the exercise questions from Class 10 Science Chapter 1 Chemical Reactions and Equations. These NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations are designed to help students build a strong foundation and score well in their board exams.

Q 1. Which of the statements about the reaction below are incorrect?

$2 \mathrm{PbO}(s)+\mathrm{C}(s) \rightarrow 2 \mathrm{~Pb}(\mathrm{~s})+\mathrm{CO}_2(g)$

(a) Lead is getting reduced.

(b) Carbon dioxide is getting oxidized.

(c) Carbon is getting oxidized.

(d) Lead oxide is getting reduced.

(i) (a) and (b)

(ii) (a) and (c)

(iii) (a), (b) and (c)

(iv) all

Answer:

$2 \mathrm{PbO}(s)+\mathrm{C}(s) \rightarrow 2 \mathrm{~Pb}(s)+\mathrm{CO}_2(g)$

In the above reaction, PbO reduces to Pb and C(carbon) gets oxidized to carbon dioxide.

Hence, statements (a) and (b) are correct.

Thus, option (i) is correct.

Q 2. $\mathrm{Fe}_2 \mathrm{O}_3+2 \mathrm{Al} \rightarrow \mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{Fe}$

The above reaction is an example of a

(a) combination reaction.

(b) double displacement reaction.

(c) decomposition reaction.

(d) displacement reaction

Answer :

$\mathrm{Fe}_2 \mathrm{O}_3+2 \mathrm{Al} \rightarrow \mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{Fe}$

The above reaction is an example of a displacement reaction.

Hence, the correct answer is option (d).

Q 3. What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.

(a) Hydrogen gas and iron chloride are produced.

(b) Chlorine gas and iron hydroxide are produced.

(c) No reaction takes place.

(d) Iron salt and water are produced.

Answer:

When dilute hydrochloric acid is added to iron fillings, then hydrogen gas and iron chloride are produced.

The reaction is given as :

$\mathrm{Fe}(s)+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{FeCl}_2(\mathrm{aq})+\mathrm{H}_2(g)$

Thus, option (a) is correct.

Q 4. What is a balanced chemical equation? Why should chemical equations be balanced?

Answer:

The chemical equation which has an equal number of atoms of all elements on both sides of the reaction is known as a balanced chemical equation.

The law of conservation of mass states that mass can neither be created nor be destroyed so chemical equations should be balanced.

Q 5. (a) Translate the following statements into chemical equations and then balance them.

Hydrogen gas combines with nitrogen to form ammonia.

Answer:

Hydrogen gas combines with nitrogen to form ammonia can be written as :

$3 \mathrm{H}_2(g)+\mathrm{N}_2(g) \rightarrow 2 \mathrm{NH}_3$

Q 5. (b) Hydrogen sulphide gas burns in the air to give water and sulfur dioxide.

Answer:

Hydrogen sulphide gas burns in air to give water and sulfur dioxide can be written as :

$2 \mathrm{H}_2 \mathrm{~S}(\mathrm{~g})+3 \mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{SO}_2(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{l})$

Q 5. (c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.

Answer:

Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate can be written as :

$3 \mathrm{BaCl}_2(\mathrm{aq})+\mathrm{Al}_2\left(\mathrm{SO}_4\right)_3(\mathrm{aq}) \rightarrow 2 \mathrm{AlCl}_3(\mathrm{aq})+3 \mathrm{BaSO}_4(s)$

Q 5. (d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.

Answer: Potassium metal reacts with water to give potassium hydroxide and hydrogen gas is given by :

$2 \mathrm{~K}(s)+2 \mathrm{H}_2 \mathrm{O}(l) \rightarrow 2 \mathrm{KOH}(\mathrm{aq})+\mathrm{H}_2$

Q 6. (a) Balance the following chemical equations.

(a) Balance the following chemical equations.

$\mathrm{HNO}_3+\mathrm{Ca}(\mathrm{OH})_2 \rightarrow \mathrm{Ca}\left(\mathrm{NO}_3\right)_2+\mathrm{H}_2 \mathrm{O}$

Answer:

The balanced chemical equation is given as :

$2 \mathrm{HNO}_3+\mathrm{Ca}(\mathrm{OH})_2 \rightarrow \mathrm{Ca}\left(\mathrm{NO}_3\right)_2+2 \mathrm{H}_2 \mathrm{O}$

Q 6. (b)Balance the following chemical equations.

$\mathrm{NaOH}+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{Na}_2 \mathrm{SO}_4+\mathrm{H}_2 \mathrm{O}$

Answer:

The balanced chemical equation is given as :

$2 \mathrm{NaOH}+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{Na}_2 \mathrm{SO}_4+2 \mathrm{H}_2 \mathrm{O}$

Q 6. (c) Balance the following chemical equations.

$\mathrm{NaCl}+\mathrm{AgNO}_3 \rightarrow \mathrm{AgCl}+\mathrm{NaNO}_3$

Answer:

The balanced chemical equation is given as :

$\mathrm{NaCl}+\mathrm{AgNO}_3 \rightarrow \mathrm{AgCl}+\mathrm{NaNO}_3$

Q 6. (d) Balance the following chemical equations.

$\mathrm{BaCl}_2+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{BaSO}_4+\mathrm{HCl}$

Answer:

A balanced chemical equation is given as :

$\mathrm{BaCl}_2+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{BaSO}_4+2 \mathrm{HCl}$

Q 7. (a) Write the balanced chemical equations for the following reactions.

(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water

Answer:

Calcium hydroxide + Carbon dioxide →Calcium carbonate + Water

The balanced chemical equation for the above reaction is given as :

$\mathrm{Ca}(\mathrm{OH})_2+\mathrm{CO}_2 \rightarrow \mathrm{CaCO}_3+\mathrm{H}_2 \mathrm{O}$

Q 7. (b) Zinc + Silver nitrate → Zinc nitrate + Silver

Answer:

Zinc + Silver nitrate → Zinc nitrate + Silver

The balanced chemical equation for the above reaction is given as :

$\mathrm{Zn}+2 \mathrm{AgNO}_3 \rightarrow \mathrm{Zn}\left(\mathrm{NO}_3\right)_2+2 \mathrm{Ag}$

Q 7. (c)Aluminium + Copper chloride → Aluminium chloride + Copper

Answer:

Aluminium + Copper chloride → Aluminium chloride + Copper

The balanced chemical equation for the above reaction is given as :

$2 \mathrm{Al}+3 \mathrm{CuCl}_2 \rightarrow 2 \mathrm{AlCl}_2+3 \mathrm{Cu}$

Q 7. (d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride

Answer:

Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride

The balanced chemical equation for the above reaction is given as :

$\mathrm{BaCl}_2+\mathrm{K}_2 \mathrm{SO}_4 \rightarrow \mathrm{BaSO}_4+2 \mathrm{KCl}$

Q 8. (a) Write the balanced chemical equation for the following and identify the type of reaction in each case.

(a) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) + Barium bromide(s)

Answer:

Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) + Barium bromide(s)

The balanced chemical equation for the above reaction is given as :

$2 K B r(a q)+B a I_2(a q) \rightarrow 2 K I(a q)+B a B r_2$

It is a double displacement reaction.

Q 8. (b) Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g)

Answer:

Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g)

The balanced chemical equation for the above reaction is given by :

$\mathrm{ZnCO}_3(s) \rightarrow \mathrm{ZnO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})$

It is a decomposition reaction.

Q 8. (c)Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)

Answer:

Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)

The balanced chemical equation for the above reaction is given by :

$\mathrm{H}_2(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g})$

It is a combination reaction.

Q 8. (d)Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)

Answer:

Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)

The balanced chemical equation for the above reaction is given by :

$\mathrm{Mg}(s)+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{MgCl}_2(\mathrm{aq})+\mathrm{H}_2(g)$

It is a displacement reaction.

Q 9. What does one mean by exothermic and endothermic reactions? Give examples.

Answer:

Exothermic reactions: Reactions in which heat is given out along with the products are called exothermic reactions.

Example : $\mathrm{CH}_4(\mathrm{~g})+2 \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CO}_2(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{g})$

Endothermic reactions: Reactions in which energy is absorbed are known as endothermic reactions.

Example: The process of photosynthesis.

$6 \mathrm{CO}_2(\mathrm{~g})+6 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightarrow \mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6(\mathrm{aq})+6 \mathrm{O}_2(\mathrm{~g})$

Q 10. Why is respiration considered an exothermic reaction? Explain.

Answer:

We know that energy is required to support life. We get energy from the food we eat.

The large molecules of food are broken into simpler substances like glucose during digestion.

Glucose and oxygen react to provide energy to the body. This reaction is a combination reaction named respiration. In this whole process, energy is released, so respiration is considered an exothermic reaction.

$\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6(\mathrm{aq})+6 \mathrm{O}_2 \rightarrow 6 \mathrm{CO}_2(\mathrm{~g})+6 \mathrm{H}_2 \mathrm{O}(\mathrm{l})+$ Energy

Q 11.Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

Answer:

In decomposition reactions, we can observe that a single reactant breaks down to give simpler products. This reaction is a source of energy. Whereas, in a combination reaction, two or more substances combine to give a product and energy is released in this reaction.

Hence, decomposition reactions are called the opposite of combination reactions.

Example : decomposition reaction : $2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{H}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g})$

And the combination reaction : $2 \mathrm{H}_2(g)+\mathrm{O}_2(g) \rightarrow 2 \mathrm{H}_2 \mathrm{O}(\mathrm{l})+$ Energy

Q 12. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.

Answer:

The decomposition reaction by heat:

$
2 \mathrm{FeSO}_4(s) \rightarrow \mathrm{Fe}_2 \mathrm{O}_3(s)+\mathrm{SO}_2(g)+\mathrm{SO}_3
$


The decomposition reaction by light :

$
2 \mathrm{AgCl}(s) \rightarrow 2 \mathrm{Ag}(s)+\mathrm{Cl}_2(g)
$


The decomposition reaction by electricity :

$
2 \mathrm{Al}_2 \mathrm{O}_3(\mathrm{aq}) \rightarrow 4 \mathrm{Al}(\mathrm{~s})+3 \mathrm{O}_2(\mathrm{~g})
$

Q 13.What is the difference between displacement and double displacement reactions? Write equations for these reactions.

Answer:

When an element displaces another element from its compound, a displacement reaction occurs.

Example : $\mathrm{Fe}(\mathrm{s})+\mathrm{CuSO}_4(a q) \rightarrow \mathrm{FeSO}_4(a q)+\mathrm{Cu}(s)$
Two different atoms or groups of atoms (ions) are exchanged in a double displacement reaction.

Example : $\mathrm{Na}_2 \mathrm{SO}_4(a q)+\mathrm{BaCl}_2(a q) \rightarrow \mathrm{BaSO}_4(s)+2 \mathrm{NaCl}(\mathrm{aq})$

Q 14.In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.

Answer:

In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. The reaction involved can be written as :

$2 \mathrm{AgNO}_3(\mathrm{aq})+\mathrm{Cu}(s) \rightarrow \mathrm{Cu}\left(\mathrm{NO}_3\right)_2(\mathrm{aq})+2 \mathrm{Ag}(s)$

Q 15. What do you mean by a precipitation reaction? Explain by giving examples.

Answer:

Any reaction that produces a precipitate is called a precipitation reaction.
Example : $\mathrm{Na}_2 \mathrm{CO}_3(\mathrm{aq})+\mathrm{CaCl}_2(\mathrm{aq}) \rightarrow \mathrm{CaCO}_3(s)+2 \mathrm{NaCl}(\mathrm{aq})$
Here, we have $\mathrm{CaCO}_3$ as precipitate so it is a precipitation reaction.

Q 16. Explain the following in terms of gain or loss of oxygen with two examples each. (a) Oxidation

Answer:

Oxidation is a reaction in which the gain of oxygen or loss of hydrogen can be observed.

Example : $2 \mathrm{Cu}+\mathrm{O}_2 \rightarrow 2 \mathrm{CuO}$

$
\mathrm{CO}_2+\mathrm{H}_2 \rightarrow \mathrm{CO}+\mathrm{H}_2 \mathrm{O}
$

Q 16. (b) Reduction

Answer:

The reaction in which the loss of oxygen or gain of hydrogen can be observed is known as the reduction reaction.

Example : $\mathrm{CuO}+\mathrm{H}_2 \rightarrow \mathrm{Cu}+\mathrm{H}_2 \mathrm{O}$

$
\mathrm{ZnO}+\mathrm{C} \rightarrow \mathrm{Zn}+\mathrm{CO}
$

Q 17. A shiny brown coloured element ‘X’ on heating in the air becomes black in colour. Name the element ‘X’ and the black-coloured compound formed.

Answer:

A shiny brown-colored element is copper (Cu) and on heating, in the air, it becomes black in colour because of the formation of copper oxide(CuO).

$2 \mathrm{Cu}+\mathrm{O}_2 \rightarrow 2 \mathrm{CuO}$

Q 18. Why do we apply paint on iron articles?

Answer:

To prevent iron from rusting, paint is applied to iron articles. After applying paint iron articles are not in contact with moisture and air and hence rusting is prevented.

Q 19. Oil and fat-containing food items are flushed with nitrogen. Why?

Answer:

We know that nitrogen is an inert gas and does not react with oil and fat-containing food. Whereas, other gases like oxygen react with the oil and fat-containing food and make them rancid. Hence, to remove oxygen and prevent food from acidic food items is flushed with nitrogen.

Q 20. Explain the following terms with one example each.

(a) Corrosion

Answer:

Corrosion is a process in which metals deteriorate due to chemical reactions with moisture, air, and chemicals. The rusting of iron is a major example of corrosion. Iron corrodes in the presence of moisture and air.

$4 \mathrm{Fe}+3 \mathrm{O}_2+\mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{Fe}_2 \mathrm{O}_3 \cdot \mathrm{H}_2 \mathrm{O}$

Q 20. (b)Rancidity

Answer:

The process of oxidation of fats and oils, which can be noticed by a change in color, smell, and taste, is known as rancidity.

Example: When butter is kept in an open atmosphere,e its smell and taste change which results in rancidity.

Practice Questions for Class 10 Science Chapter 1

NCERT Class 10 Chemical Reactions and Equations practice questions are given below they are designed as per the latest Class 10 NCERT syllabus.

Question 1. State the change that is observed when a China dish containing copper powder is heated over the flame of a burner. Name the phenomenon responsible for the change and write a balanced equation for the chemical reaction that occurs. How is this reaction different from the reaction that occurs when copperware kept in open air slowly loses its shiny brown surface and gains a coat? Write the chemical name of the coating and state its colour.

Answer:

When a China dish containing copper powder is heated, it undergoes oxidation. Copper reacts with oxygen in the air to form copper(II) oxide, which is black in color.

Balanced Equation for the Reaction:

$2 \mathrm{Cu}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{CuO}(\mathrm{s})$

The reason behind this is oxidation of copper in the presence of oxygen

On the other hand, when copper wares are kept in the open air, they react with carbon dioxide, oxygen, and moisture, they slowly tarnish and form a greenish coating. This greenish coating is basic copper carbonate.

Chemical Equation for Tarnishing: $2 \mathrm{Cu}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{CuCO}_3 \cdot \mathrm{Cu}(\mathrm{OH})_2(\mathrm{~s})$

Question 2. A chemical compound ' X ' is used to bleach washed clothes in laundry as well as to make drinking water free from germs. Identify ' X '. How is this compound represented? Write the method of its preparation along with the chemical equation for the reaction that occurs.

Answer:

The compound 'X' used to bleach clothes and purify drinking water is bleaching powder (also called calcium oxychloride).

Representation

X= Bleaching powder ($\mathrm{CaOCl}_2$)

Preparation Method: Bleaching powder is prepared by passing chlorine gas over dry slaked lime (calcium hydroxide).

Reaction is as follows:

$2 \mathrm{Cl}_2+2 \mathrm{Ca}(\mathrm{OH})_2 \rightarrow \mathrm{CaCl}_2+\mathrm{CaOCl}_2+2 \mathrm{H}_2 \mathrm{O}$

Question 3. Study the following cases :
(i) $\mathrm{CuSO}_4+\mathrm{Mg} \longrightarrow$
(ii) $\mathrm{FeSO}_4+\mathrm{Pb} \longrightarrow$
(iii) $\mathrm{CaSO}_4+\mathrm{Al} \longrightarrow$
(iv) $\mathrm{ZnSO}_4+\mathrm{Ca} \longrightarrow$

The case/cases in which new product(s) will form is/are :

(1) Only (i)

(2) Only (iii)

(3) (i) and (iv)

(4) (i), (ii) and (iv)

Answer:

Let us look at which reactions will give new products. This happens when a more reactive metal replaces a less reactive one in a compound.

(i) CuSO₄ + Mg →

$\mathrm{Mg}+\mathrm{CuSO}_4 \rightarrow \mathrm{MgSO}_4+\mathrm{Cu}$
Magnesium is more reactive than copper → reaction happens → new product forms

(ii) FeSO₄ + Pb →
Lead is less reactive than iron → no reaction → no new product

(iii) CaSO₄ + Al →
Aluminium is less reactive than calcium → no reaction → no new product

(iv) ZnSO₄ + Ca →

$\mathrm{Ca}+\mathrm{ZnSO}_4 \rightarrow \mathrm{CaSO}_4+\mathrm{Zn}$
Calcium is more reactive than zinc → reaction happens → new product forms

Hence, the correct answer is option 3).

Approach to Solve Questions of Class 10 Science Chapter 1

To score good marks in exams, it is important to understand the correct method of solving questions from Class 10 Science Chapter 1, Chemical Reactions and Equations. These approaches help students apply concepts logically, balance equations accurately, and identify types of reactions.

1. Understand the basic topics
Before solving questions from Class 10 Science Chapter 1 Chemical Reactions and Equations, it is important to understand fundamental concepts like reactants, products, chemical changes, and types of chemical reactions for a strong conceptual foundation.

2. Identify the type of reactions

Having a clear understanding of the types of Chemical reactions is important for solving the NCERT Class 10 Science Chapter 1 Chemical Reactions and Equations. There are different kinds of reactions like:

(i). Combination: $A+B \rightarrow A B$

(ii). Decomposition: $A B \rightarrow A+B$

(iii). Displacement: $A+B C \rightarrow A C+B$

(iv). Double Displacement: $A B+C D \rightarrow A D+C B$

(v). Redox : Identify the species that is oxidized/reduced.

3. Balancing of Chemical Equations

Questions from balancing of chemical equations are asked frequently in exams to solve them effectively first convert the word equation into a chemical equation and balance it by ensuring equal atoms of each element on both sides.

4. Note indicators of Chemical Changes

To identify whether the change is Physical or Chemical, note down the indicators such as change in colour, evolution of gas, precipitate formation, or temperature change to identify reactions practically.

5. Practice questions

Practice again and again, as it will help in mastering Chapter 1, Chemical Reactions and Equations. Start with simpler problem,s then gradually move to difficult ones. NCERT Chapter 1 Chemical Reactions and Equations questions are asked directly in the CBSE and State board exams.

Topics and Subtopics Covered in the NCERT Textbook

All the topics and subtopics covered in the NCERT Class 10 Science Chapter 1 Chemical Reactions and Equations are listed below:

1.1. Chemical equations
1.1.1. Writing a Chemical Equation
1.1.2. Balanced Chemical Equations

1.2. Types of Chemical Reactions
1.2.1. Combination Reaction
1.2.2. Decomposition Reaction
1.2.3. Displacement Reaction
1.2.4. Double Displacement Reaction
1.2.5. Oxidation and Reduction

1.3. Have you observed the effects of oxidation reactions in everyday life?
1.3.1. Corrosion
1.3.2. Rancidity

NCERT Class 10 Science Chapter 1: Important Reactions And E-book

Important Formulas from Class 10 Science Chapter 1 Chemical Reactions and Equations are listed below. Go through them to make your basic concept more concrete.

TYPES OF CHEMICAL REACTIONS

  1. Combination or Addition reaction: A + B → AB

  2. Decomposition Reaction: AB → A + B

  3. Displacement Reaction: A + BC → AC + B

  4. Double Displacement Reaction or Precipitation Reaction:

AgNO3 + NaCl → AgCl(s) + NaNO3

  1. Oxidation and Reduction reactions:

1689918712213

To download the E-book click on the link given below:

NCERT Solutions for Class 10

The hyperlinks to the NCERT solution of class 10 for other subjects are given below.

NCERT Books and NCERT Syllabus

Students can refer to the links given below for the NCERT books and Syllabus.

Frequently Asked Questions (FAQs)

Q: What are the different types of chemical reactions?
A:

The main types of chemical reactions include combination reactions, decomposition reactions, displacement reactions, and redox reactions.

Q: What are chemical reactions?
A:

Chemical reactions are processes where reactants transform into products. This transformation involves the breaking and forming of chemical bonds, resulting in a change in the chemical composition of substances.

Q: What is the importance of balancing chemical equations in Class 10 Science Chapter 1 Chemical Reactions and Equations?
A:

Balancing chemical equations is important because it ensures that the law of conservation of mass is upheld. According to this law, mass can neither be created nor destroyed in a chemical reaction. Therefore, the number of atoms of each element must be the same on both sides of the equation.

Q: Why is the concept of oxidation and reduction important in NCERT Chapter 1 Chemical Reactions and Equations? ?
A:

Oxidation and reduction are important because they describe the transfer of electrons between substances. This process explains how energy is transferred in chemical reactions.

Q: What role do catalysts play in chemical reactions?
A:

Catalysts are substances that speed up chemical reactions without being consumed in the process. They work by lowering the activation energy required for the reaction to occur, making it faster.

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