NCERT Solutions for Chapter 1 Chemical Reactions and Equations Class 10 Science
Book Solutions
Chapter 1 Chemical Reactions and Equations NCERT Solutions Class 10 Science
We need to study the NCERT Solutions for Chapter 1 Chemical Reactions and Equations of Class 10 Science Textbook. This is very important for the students who are studying in CBSE schools. This chapter will provide the students with the basic idea of how chemical reactions can be written in the text form. Also, it will let the students know about the day to day reactions taking place in our surroundings. By studying the NCERT Solutions of this chapter, one could be able to answers the questions related to chemical reactions and equations which could be asked in the examination.
NCERT Solutions for Chemical Reactions and Equations Class 10 Science
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Chapter Name |
NCERT Solutions for Chapter 1 Chemical Reactions and Equations |
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Class 10 Science |
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Topics covered in the Chapter |
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Related Readings |
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These NCERT Solutions of Class 10 NCERT Science Textbook is based on the latest syllabus of CBSE. One could study these questions and answers of chemical reactions and equations to give their best shot in the examination. One could also take help from the Revision Notes provided of this chapter to study well. These could be found on the links given in this page.
1
Why should a magnesium ribbon be cleaned before burning in air?
Answer
Magnesium is a very reactive metal. So, when it is stored, it reacts with oxygen in the presence of air to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. Therefor, magnesium ribbon is cleaned in order to remove the layer of magnesium oxide so that it can burn in air.
2
Answer
(i) H2 (g) + Cl2 (g) → 2HCl (g)
(ii) 3BaCl2 (s) + Al2(SO4)3 (s) → 3BaSO4 (s) + 2AlCl3 (s)
(iii) 2Na(s) + 2H2O (l) → 2NaOH (aq) + H2 (g)
3
Write a balanced chemical equation with state symbols for the following reactions.
(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.
Answer
(i) BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)
(ii) NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l)
aq: aqueous solution
l: liquid
1
A solution of a substance ‘X’ is used for whitewashing.
(i) Name the substance ‘X’ and write its formula.
(ii) Write the reaction of the substance ‘X’ named in (i) above with water.
Answer
(i) The substance ‘X’ which is used for whitewashing is quick lime or calcium oxide. Its chemical formula is CaO.
(ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).
CaO (s) + H2O (l) → Ca(OH)2 (aq)
Calcium Oxide (Quick Lime) + Water → Calcium Hydroxide (Slaked Lime)
2
Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.
Answer
Chemical formula of water is H2O. Thus, one molecule of water contains two parts of hydrogen and one part oxygen. Therefore during the electrolysis of water, the amount of hydrogen gas collected in one of the test tubes is double than that of the oxygen collected in the other test tube.
1
Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Answer
Iron is more reactive than copper. Therefore, when an iron nail is dipped in the copper sulphate solution then iron displaces copper from the copper sulphate and new compound ferrous suplphate is formed. Therefore the colour of the copper sulphate solution changes.
The reaction involved here is:
Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
2
Give an example of a double displacement reaction other than the one given in Activity 1.10.
Answer
2KBr (aq) + BaI2 (aq) → 2KI (aq) + BaBr2 (aq)
Here, Potassium(K) and Barium(Ba) exchanges their ions.
3
Identify the substances that are oxidised and the substances that are reduced in the following reactions.
(i) 4Na(s) + O2 (g) → 2Na2O(s)
(ii) CuO(s) + H2 (g) → Cu(s) + H2O(l)
Answer
(i) Sodium(Na) is oxidised as it gains oxygen and oxygen gets reduced.
(ii) Copper oxide (CuO) is reduced to copper (Cu) while hydrogen (H2) gets oxidised to water as it gains water (H2O).
1
Which of the statements about the reaction below are incorrect?
2PbO (s) + C (s) → 2Pb (s) + CO2 (g)
(a) Lead is getting reduced.
(b) Carbon dioxide is getting oxidised.
(c) Carbon is getting oxidised.
(d) Lead oxide is getting reduced.
(i) (a) and (b)
(ii) (a) and (c)
(iii) (a), (b) and (c)
(iv) all
Answer
The option (i) is correct.
The question asks which option is incorrect. Here, Lead oxide(PbO) is getting reduced to Lead(Pb) and Carbon(C) is getting oxide to Carbon dioxide (CO2).
2
Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a
(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.
Answer
Option (d) is correct.
Here, Aluminium(Al) displaces Iron(Fe) from Fe2O3. Thus, it is a displacement reaction.
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
Correct option is (a).
4
What is a balanced chemical equation? Why should chemical equations be balanced?
Answer
A reaction in which the number of atoms of each element is equal on both sides of the chemical equation is equal is called a balanced chemical equation.
For Example:
2Mg(s) + O2(g) → 2MgO(s)
Here, there are 2 atoms of Mg and 2 atoms of O on right hand side of the equation. Also, on the left hand side of the equation, there are 2 atoms of Mg and O respectively. Thus, it is a balanced equation.
The chemical equations should be balanced because it follows law of conservation of mass. According to this law, the total mass of reactants must be equal to the total mass of the products.
5
Translate the following statements into chemical equations and then balance them.
Answer
(a) H2(g) + N2(g) → NH3(g)
Balanced equation: 3H2 (g) + N2 (g) → 2NH3 (g)
(b) H2S(g) + O2(g) → H2O(l) + SO2(g)
Balanced equation: 2H2S (g) + 3O2 (g) → 2H2O (l) + 2SO2 (g)
(c) BaCl2(aq) + Al2(SO4)3 (aq) → AlCl3 (aq) + BaSO4 (s)
Balanced equation: 3BaCl2 (aq) + Al2(SO4)3 (aq) → 2AlCl3 (aq) + 3BaSO4 (s)
(d) K (s) + H2O (l) → KOH (aq) + H2 (g)
Balanced Equation: 2K (s) + 2H2O (l) → 2KOH (aq) + H2 (g)
6
Balance the following chemical equations.
(i) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
(ii) NaOH + H2SO4 → Na2SO4 + H2O
(iii) NaCl + AgNO3 → AgCl + NaNO3
(iv) BaCl2 + H2SO4 → BaSO4 + HCl
Answer
(i) 2HNO3 (aq) + Ca(OH)2 (aq) → Ca(NO3)2 (aq) + 2H2O (l)
(ii) 2NaOH(aq) +H2SO4(aq) → Na2SO4(aq) +2H2O(l)
(iii) NaCl(aq) +AgNO3(aq) → AgCl(s) +NaNO3(aq)
(iv) BaCl2(aq) +H2SO4(aq) → BaSO4(s) +2HCl(aq)
How to Balance Chemical equations?
HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
Step 1: Note down the number of atoms on both RHS and LHS side of each elements in a table.
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Elements |
RHS |
LHS |
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H |
3 |
2 |
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N |
1 |
2 |
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O |
5 |
7 |
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Ca |
1 |
1 |
Step 2: Start with balancing the atoms which is more in number. Here, it is oxygen.
2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O
Step 3: Oxygen is balanced. Also, you can see all the elements have been balanced just by balancing the oxygen. Now, we will just add the physical state. Thus, the balanced equation will be:
2HNO3(aq) +Ca(OH)2(aq) → Ca(NO3)2(aq) +2H2O(l)
7
Write the balanced chemical equations for the following reactions.
(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water
(b) Zinc + Silver nitrate → Zinc nitrate + Silver
(c) Aluminium + Copper chloride → Aluminium chloride + Copper
(d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride
Answer
(a) Ca(OH)2(aq) +CO2(g) → CaCO3(s) +H2O(l)
(b) Zn(s) +2AgNO3(aq) → Zn(NO3)2(aq) +2Ag(s)
(c) 2Al(s) +3CuCl2(aq) → 2AlCl3(aq) +3Cu(s)
(d) BaCl2(aq) +K2SO4(aq) → BaSO4(s) +2KCl(aq)
8
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)
(b) Zinc carbonate (s) → Zinc oxide (s) + Carbon dioxide (g)
(c) Hydrogen (g) + Chlorine (g) → Hydrogen chloride (g)
(d) Magnesium (s) + Hydrochloric acid (aq) → Magnesium chloride (aq) + Hydrogen (g)
Answer
(a) 2KBr (aq) + BaI2 (aq) → 2KI (aq) + BaBr2 (s)
This reaction is Double displacement reaction because in this reaction, Potassium (K) and Barium (Ba) exchanged their ions.
(b) ZnCO3 (s) → ZnO (s) + CO2 (g)
This is Decomposition reaction because a single reactant, ZnCO3 gives two simple products.
(c) H2 (g) + Cl2 (g) → 2HCl (g)
This is a Combination reaction as Hydrogen(H) and Chlorine(Cl) combine together to form HCl.
(d) Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)
This is Displacement Reaction as Magnesium (Mg) displaces Hydrogen (H) to Magnesium Chloride (MgCl2).
9
What does one mean by exothermic and endothermic reactions? Give examples.
Answer
Chemical reactions in which the energy is released in the form of heat, light, or sound are called exothermic reactions.
Example: C (g) + O2 (g) → CO2 + Heat Energy
Chemical reactions in which energy is absorbed or it requires energy in order to form products are called endothermic reactions.
Example:
10
Why is respiration considered an exothermic reaction? Explain.
Answer
Respiration is considered as an exothermic reaction because in respiration, oxidation of glucose takes place to produces heat energy. So as heat energy is released, respiration is an exothermic reaction.
C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H2O (l) + Energy
11
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Answer
In Decomposition reactions, a single compound breaks down to form two or more substances while in in combination reactions, two or more substances combine to give a single new substance.
Also, decomposition reactions require a source of energy to proceed while in combination reactions, there is release of energy.
For Example:
Decomposition Reaction:
Combination Reaction:
CaO (s) + H2O (l) → Ca(OH)2 (aq)
12
Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
Answer
13
What is the difference between displacement and double displacement reactions? Write equations for these reactions.
Answer
In a displacement reaction, a more reactive element displaces a less reactive element from a compound.
For Example:
CuSo4 (aq) + Zn (s) → ZnSO4 (aq) + Cu (s)
In a double displacement reaction, there is exchange of ions between two reactants to form new compounds.
For Example:
Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + 2NaCl (aq)
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
2AgNO3 (aq) + Cu (s) → Cu(NO3)2 (aq) + 2Ag (s)
Silver Nitrate + Copper → Copper Nitrate + Silver
15
What do you mean by a precipitation reaction? Explain by giving examples.
Answer
A reaction in which an insoluble solid product (also called precipitate) is formed is called a precipitation reaction. It is also indicated by downward arrow.
For Example:
Na2CO3 (aq) + CaCl2 (aq) → CaCO3 (↓) + 2NaCl (aq)
Sodium Carbonate + Calcium Chloride → Calcium Carbonate + Sodium Chloride
AgNO3 (aq) + NaCl (aq) → AgCl (↓) + NaNO3 (aq)
Silver nitrate + Sodium chloride → Silver chloride + Sodium nitrate
16
Explain the following in terms of gain or loss of oxygen with two examples each.
(a) Oxidation
(b) Reduction
Answer
Oxidation Reaction: It is a chemical reaction in which a substance gains oxygen or loses hydrogen.
Here, Magnesium is oxidised to become Magnesium Oxide.
Here, Copper is oxidised to become Copper Oxide.
Reduction Reaction: It is a chemical reaction in which as substance loses oxygen or gain hydrogen takes place.
Here, Copper oxide is reduced to become Copper.
Here, Zinc oxide is reduced to become Zinc.
17
A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.
Answer
The element ‘X’ is copper (Cu) and the black-coloured compound formed is copper oxide (CuO). The equation of the reaction involved on heating copper is given below.
18
Why do we apply paint on iron articles?
Answer
Iron articles are painted because it prevents them from rusting. When paint is applied, the surface of iron articles does not come in contact of moisture and. Hence, rusting is prevented.
19
Oil and fat containing food items are flushed with nitrogen. Why?
Answer
Oil and fat containing food items flushed with nitrogen in order to protect them from being oxidised. Nitrogen acts as an antioxidant and prevent their contact with oxygen or air.
20
Explain the following terms with one example each.
(a) Corrosion
(b) Rancidity
Answer
Corrosion: It is a process where materials, usually metals, deteriorate as a result of a chemical reaction with air, moisture, chemicals, etc.
For example:
Iron in the presence of moisture, reacts with oxygen to form hydrated iron oxide.
4Fe + 3O2 + nH2O → 2Fe2O3.nH2O
Rancidity: It is the process of oxidation of fats and oils with oxygen or air that can be easily noticed by the change in taste and smell.
For example: the taste and smell of curd changes when kept for long.
Above mentioned NCERT Solutions for Chapter 1 Chemical Reactions and Equations are very important for the students who want to get good marks in the examination. They can study those NCERT Solutions in order to excel in Science subject. We have also provided solutions of different chapter of Class 10 Science Textbook published by NCERT.
NCERT Textbooks Solutions for Class 10 Science
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Chapter 2 Acids, Bases and Salts |
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Chapter 3 Metals and Non-metals |
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Chapter 4 Carbon and its Compounds |
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Chapter 5 Periodic Classification of Elements |
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Chapter 6 Life Processes |
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Chapter 7 Control and Coordination |
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Chapter 8 How do Organisms Reproduce? |
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Chapter 9 Heredity and Evolution |
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Chapter 10 Light – Reflection and Refraction |
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Chapter 11 The Human Eye and the Colourful World |
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Chapter 12 Electricity |
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Chapter 13 Magnetic Effects of Electric Current |
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Chapter 14 Sources of Energy |
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Chapter 15 Our Environment |
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Chapter 16 Sustainable Management of Natural Resources |
Students can click on the above link to access the chapter solutions of those chapters. These NCERT Solutions are as per the latest syllabus prescribed by CBSE. Also, it enhance the ability of a child to study more efficiently and in a better way. Students can also access to important questions and answers of Chapter 1 Chemical Reactions and Equation provided by this website. These are also very important in examination.
There are various types of questions that could be asked in the examination which includes short answer type questions (SAQ), multiple choice questions (MCQ), Long Answer Type questions (LAQ), Activity based questions and Practical Based Questions. Students must aware of all these types of questions and practice according to it.