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

 

NCERT solutions for class 10 science chapter 1 Chemical Reactions and Equations: Scoring full marks in this chapter will be easy if you have on hand the NCERT free solutions for class 10 science chapter 1 chemical reactions and equations and know-how to answer the questions asked in the school and board exams. As per the previous year's paper analysis and student's feedback, this chapter has a good weightage and mostly practice-based questions are going to be asked in the exam. The CBSE NCERT solutions for class 10 science chapter 1 Chemical Reactions and Equations help you to solve the chemical equations. Through NCERT solutions for class 10 science chapter 1 Chemical Reaction and Equation, you will also get to know why balancing in between chemical equations is important. The 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 equations must always be balanced. The solutions for NCERT class 10 science chapter 1 Chemical Reaction and Equation provides an overview of the main concepts mentioned in the chapter and helps you to get well versed with important topics such as writing chemical equations and balancing them. 

If you want to score well in your board and competitive exam, then you don't need to worry, NCERT Solutions will help you. 

NCERT class 10 science chapter 1 (Chemical Reactions and Equations) - Important Topics

Topics covered in this chapter are:

  • Chemical reactions and equations
  • Chemical equations
  • Types of chemical equations
  • Effects of oxidation reactions in everyday life?

NCERT Questions & Answers of Class 10 Science : Chapter 1 Chemical Reactions & Equations

Topic 1.1  Chemical equations:

Q 1Why should a magnesium ribbon be cleaned before burning in 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 stable oxide so prevent 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 as :

H_2(g)+Cl_2(g)\rightarrow 2HCl(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 as :

3BaCl_2(s)+Al_2(SO_4)_3(g)\rightarrow 3BaSO_4(s)+2AlCl_3(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 as :

2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq)+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 of  solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride is given by :

BaCl_2(aq)+Na_2SO_4(aq)\rightarrow BaSO_4(s)+2NaCl(aq)

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 :

NaOH(aq)+HCl(aq)\rightarrow NaCl (aq)+H_2O(l)

CBSE NCERT solutions for science class 10 science Chapter 1 Chemical Reaction and Equation 

Topic 1.2 Types of chemical reactions

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 :

CaO(s)+H_2O(l)\rightarrow Ca(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 first one.

NCERT textbook solutions for class 10 science chapter 1 Chemical Reaction and Equation 

Topic 1.3 Have you observed the effects of an oxidation reaction in everyday life?

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

Answer:

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

CuSO_4(aq)+Fe(s)\rightarrow FeSO_4(aq)+Cu(s)

The colour change 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 :

Na_2CO_3(aq)+CaCl_2(aq)\rightarrow CaCO_3(s)+2NaCl(aq)

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

4Na(s)+O_{2}\rightarrow 2Na_{2}O(s)

Answer:

4Na(s)+O_{2}\rightarrow 2Na_{2}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.

CuO(s)+H_{2}(g)\rightarrow Cu(s)+H_{2}O(l) 

Answer:

CuO(s)+H_{2}(g)\rightarrow Cu(s)+H_{2}O(l)

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

Solutions for NCERT  class 10 science chapter 1 Chemical Reactions and Equations- Exercise solutions

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

            2PbO(s)+C(s)\rightarrow 2Pb(s)+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:

2PbO(s)+C(s)\rightarrow 2Pb(s)+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.      Fe_{2}O_{3}+2Al\rightarrow Al_{2}O_{3}+2Fe The above reaction is an example of a

            (a) combination reaction.

            (b) double displacement reaction. 

            (c) decomposition reaction.

            (d) displacement reaction

Answer:

Fe_{2}O_{3}+2Al\rightarrow Al_{2}O_{3}+2Fe

The above reaction is an example of a displacement reaction.

Hence, option (d) is correct.

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 :

Fe(s)+2HCl(aq)\rightarrow FeCl_2(aq)+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 :

3H_2(g)+N_2(g)\rightarrow 2NH_3

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

Answer:

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

2H_2S(g)+3O_2(g)\rightarrow 2SO_2(g)+2H_2O(l)

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

Answer:

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

3BaCl_2(aq)+Al_2(SO_4)_3(aq)\rightarrow 2AlCl_3(aq)+3BaSO_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 :

2K(s)+2H_2O(l)\rightarrow 2KOH(aq)+H_2

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

    Balance the following chemical equations. (a)

       HNO_{3}+Ca(OH)_{2}\rightarrow Ca(NO_{3})_{2}+H_{2}O 

Answer:

  The balanced chemical equation is given as :

2HNO_{3}+Ca(OH)_{2}\rightarrow Ca(NO_{3})_{2}+2H_{2}O

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

        NaOH + H_{2}SO_{4} \rightarrow Na_{2}SO_{4} + H_{2}O

Answer:

  The balanced chemical equation is given as :

        2NaOH + H_{2}SO_{4} \rightarrow Na_{2}SO_{4} + 2H_{2}O

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

     NaCl+AgNO_{3}\rightarrow AgCl+NaNO_{3}

Answer:

  The balanced chemical equation is given as :

       NaCl+AgNO_{3}\rightarrow AgCl+NaNO_{3}

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

     BaCl_{2}+H_{2}SO_{4}\rightarrow BaSO_{4}+HCl

Answer:

  A balanced chemical equation is given as :

  BaCl_{2}+H_{2}SO_{4}\rightarrow BaSO_{4}+2HCl

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 equations for the above reaction is given as :

   Ca(OH)_2+CO_2\rightarrow CaCO_3+H_2O

  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 :

    Zn+2AgNO_3\rightarrow Zn(NO_3)_2+2Ag

  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 :

   2Al+3CuCl_2\rightarrow2 AlCl_2+3Cu

  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 :

  BaCl_2+K_2SO_4\rightarrow BaSO_4+2KCl

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 :

   2KBr(aq)+BaI_2(aq)\rightarrow 2KI(aq)+BaBr_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 : 

   ZnCO_3(s)\rightarrow ZnO(s)+CO_2(g)

   It is 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 : 

  H_2(g)+Cl_2(g)\rightarrow 2HCl(g)

  It is 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 : 

   Mg(s)+2HCl(aq)\rightarrow MgCl_2(aq)+H_2(g)

   It is 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 : CH_4(g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2O (g)

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

   Example: The process of photosynthesis.

   6CO_2 (g) +6H_2O(g)\rightarrow C_6H_1_2O_6(aq) + 6O_2 (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 a simpler substance like glucose during digestion.

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

   C_6H_1_2O_6(aq)+6O_2\rightarrow 6CO_2(g)+6H_2O(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 source of energy. Whereas, in combination reaction two or more substances combine to give a product and energy is released in this reaction.

 Hence, decomposition reactions called the opposite of combination reactions.

 Example : 

  decomposition reaction : 2H_2O(l)\rightarrow 2H_2(g)+O_2(g)

  and the combination reaction : 2H_2(g)+O_2(g)\rightarrow 2H_2O(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:

  2FeSO_4(s)\rightarrow Fe_2O_3(s)+SO_2(g)+SO_3

  The decomposition reaction by light :

   2AgCl(s)\rightarrow 2Ag(s)+Cl_2(g)

   The decomposition reaction by electricity :

    2Al_2O_3(aq)\rightarrow 4Al(s)+3O_2(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 : Fe(s) + CuSO_4(aq) \rightarrow FeSO_4(aq) + Cu(s)

  Two different atoms or groups of atoms (ions) are exchanged in a double displacement reaction.

 Example :Na_2SO_4(aq) + BaCl_2(aq) \rightarrow BaSO_4(s) + 2NaCl(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 :

2AgNO_3(aq)+Cu(s)\rightarrow Cu(NO_3)_2(aq)+2Ag(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 : Na_2CO_3(aq)+CaCl_2(aq)\rightarrow CaCO_3(s)+2NaCl(aq)

 Here, we have CaCO_3  as precipitate so it is a precipitation reaction.

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

Oxidation 

 Answer:

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

  Example :2Cu + O_2 \rightarrow 2CuO 

              CO_2+H_2\rightarrow CO+H_2O

 Q 16.(b)     Reduction

 Answer:

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

  Example : CuO +H_2 \rightarrow Cu+H_2 O

                 ZnO + C\rightarrow Zn+ 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).

 2Cu+O_2\rightarrow 2CuO

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 the 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 acidity food items are flushed with nitrogen.

Q 20.(a)     Explain the following terms with one example each.

Corrosion 

Answer:

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

  4Fe+3O_2+H_2O\rightarrow 2Fe_2O_3.H_2O

Q 20. (b)     Rancidity

Answer:

(b)     Rancidity

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 the open atmosphere than its smell and taste change which results in rancidity.

NCERT Solutions for Class 10 Science - Chapter wise

Chapter No.

Chapter Name

Chapter 1

CBSE NCERT solutions for class 10 science chapter 1 Chemical Reactions and Equations

Chapter 2

NCERT free solutions for class 10 science chapter 2 Acids, Bases, and Salts

Chapter 3

NCERT textbook solutions for class 10 science chapter 3 Metals and Non-metals

Chapter 4

Solutions for NCERT class 10 science chapter 4 Carbon and Its Compounds

Chapter 5

CBSE solutions for class 10 science chapter 5 Periodic Classification of Elements

Chapter 6

NCERT free solutions for class 10 science chapter 6 Life Processes

Chapter 7

NCERT textbook solutions for class 10 science chapter 7 Control and Coordination

Chapter 8

Solutions for NCERT class 10 science chapter 8 How do Organisms Reproduce?

Chapter 9

NCERT free solutions for class 10 science chapter 9 Heredity and Evolution

Chapter 10

CBSE NCERT solutions for class 10 science chapter 10 Light Reflection and Refraction

Chapter 11

Solutions for NCERT class 10 science chapter 11 The Human Eye and The Colorful World

Chapter 12

NCERT solutions for class 10 science chapter 12 Electricity

Chapter 13

NCERT textbook solutions for class 10 science chapter 13 Magnetic Effects of Electric Current

Chapter 14

Solutions for NCERT solutions for class 10 chapter 14 Sources of Energy

Chapter 15

NCERT free solutions for class 10 science chapter 15 Our Environment

Chapter 16

CBSE NCERT solutions for class 10 science chapter 16 Sustainable Management of Natural Resources

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