NCERT Solutions for Class 10 Science Chapter 1 – Chemical Reactions and Equations
Last Updated :
18 Oct, 2023
NCERT Solutions for Chapter 1 Chemical Reactions and Equations is the article that provides all the solutions from the NCERT textbook with the intent to help students in their academic journey. All the problems in the NCERT book’s exercise at the end of the chapter are discussed in detail here which helps students clear their doubts regarding the solution of the problems.
The topics covered in the ‘Chemical Reactions and Equations’ chapter in Class 10 Chemistry are:
Exercise: Chemical Reactions and Equations
Q1. 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 the above
Solution:
As Lead (Pb) is losing oxygen, it undergoes reduction, whereas carbon is gaining oxygen to form carbon dioxide. Thus lead oxide is getting reduced and carbon is getting oxidised.
Option (ii) is the correct answer.
Q2. 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
Solution:
In this reaction, aluminium (Al) being a more reactive metal than Fe, displaces iron (Fe) from iron oxide (Fe2O3) and reacts with oxygen to form aluminium oxide (Al2O3). As only one metal is being displaced here, it is a displacement reaction.
Thus option (d) is the correct answer.
Q3. What happens when dilute hydrochloric acid is added to iron fillings? 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.
Solution:
When dilute Hydrochloric acid (HCl) is added to iron fillings (Fe), following reaction takes place:
Fe + HCl (dil.) → FeCl2 + H2 (g)
Thus it leads to formation of ferrous chloride and hydrogen gas.
Thus option (a) is the correct answer.
Q4. What is a balanced chemical equation? Why should a chemical equation be balanced?
Solution:
An equation in which all the elements in the compounds on both sides of the chemical equation i.e. reactants and products are equal is called a balanced equation. Chemical equation should be balanced to uphold the law of conservation of mass during a chemical reaction.
Q5. Translate the following statements into chemical equations and balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in the air to give water and sulphur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give Aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and Hydrogen gas.
Solution:
The balanced chemical equations for the given reactions are as follows:
a) 3H2 + N2 → 2NH3
b) 2H2S + 3O2 → 2H2O + 2SO2
c) 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4
d) 2K + 2H2O → 2KOH + H2
Q6. Balance the following chemical equations.
(a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
(b) NaOH + H2SO4 → Na2SO4 + H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + HCl
Solution:
The balanced chemical equations for the given reactions are as follows:
(a) 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O
(b) 2NaOH + H2SO4 → Na2SO4 + 2H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + 2HCl
Q7. Write the balanced chemical equation 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
Solution:
The balanced chemical equations for the given reactions are as follows:
(a) 2Ca(OH)2 + 2CO2 → 2CaCO3 + 2H2O
(b)Zn + 2AgNO3 → Zn(NO3)2 + 2Ag
(c) 2Al + 3CuCl2 → 2AlCl3 + 3Cu
(d) BaCl2 + K2SO4 → BaSO4 + 2KCl
Q8. Write a balanced chemical equation for the following and identify the type of reaction of each case.
a) KBr + BaI2 → KI + BaBr2
b) ZnCO3 → ZnO + CO2
c) H2 + Cl → HCl
d) Mg + HCl → MgCl2 + H2
Solution:
The balanced chemical equations along with the type of reaction for the given reactions are as follows:
a) 2KBr + BaI2 → 2KI + BaBr2 (It is a double displacement reaction)
b) ZnCO3 → ZnO + CO2 (It is a decomposition reaction)
c) H2 + Cl → 2HCl (It is a combination reaction)
d) Mg + 2HCl → MgCl2 + H2 (It is a displacement reaction)
Q9. What is meant by exothermic and endothermic reactions? Give examples.
Solution:
The reaction in which heat or energy is released in the surroundings is called exothermic reaction. For example, burning of wood, reaction of HCl and water, etc. The reaction in which heat or energy is absorbed from the surroundings is called endothermic reaction. For example, melting of ice, evaporation of liquid, etc.
Q10. Why is respiration considered to be an exothermic reaction?
Solution:
During respiration, the food broken down to glucose during digestion reacts with oxygen to form carbon dioxide, water and energy. Thus energy is released during respiration. Hence respiration is an exothermic reaction.
C6H12O6 → CO2 + H2O + Δ(Energy)
Q11. Why are decomposition reactions called the opposite of Combination reactions? Write equations for decomposition reactions.
Solution:
In a combination reaction, two or more reactants combine to form a product whereas in a decomposition reaction, a reactant breaks into two or more products. Thus decomposition reaction is the opposite of combination reaction. Some equations for decomposition reactions are:
- C6H12O6 → CO2 + H2O + Δ(Energy)
- ZnCO3 → ZnO + CO2
Q12. Write one equation each for decomposition reactions in which energy is supplied in the form of heat, light or electricity.
Solution:
The required chemical equations are as follows:
- When energy is supplied in the form of heat, it is called thermal decomposition reaction
2KClO3 + Δ → 2KCl + 3O2
- When energy is supplied in the form of electricity, it is called thermal electrolytic decomposition reaction
NaCl → Na + Cl2
- When energy is supplied in the form of light, it is called photodecomposition reaction
H2O2 → H2 + O2
Q13. What is the difference between displacement and double displacement reactions? Write relevant equations for the above.
Solution:
The difference between displacement and double displacement reaction is as follows:
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In this reaction, a more reactive element displaces a less reactive element from its compound.
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In this reaction, two elements displace each other from their compounds and form new compounds.
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In it, the displacement of one element takes place.
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In it, both the elements perform a mutual exchange of ions to form new products.
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Example:
CuSO4 + Zn → Cu + ZnSO4
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Example:
AgNO3 + NaCl → AgCl + NaNO3
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Q14. In the refining of Silver, the recovery of silver from Silver nitrate solution involves displacement reaction by Copper metal. Write down the reaction involved.
Solution:
The reaction involved in this process is:
AgNO3 (silver nitrate) + Cu (copper) → CuNO3 (copper nitrate) + Ag (silver)
Q15. What do you mean by a precipitation reaction? Explain by giving examples.
Solution:
Sometimes in a reaction, the product formed is in solid state and settles at the bottom of the container. It is called precipitate and the reaction is thus termed as precipitation reaction. For example, the reaction of sodium hydroxide and magnesium chloride forms a white precipitate of magnesium hydroxide.
NaOH + MgCl2 → NaCl + Mg(OH)2
Q16. Explain the following in terms of the gain of oxygen with two examples each.
(a) Oxidation (b) Reduction
Solution:
(a) Oxidation: When oxygen is added to a compound or element, it is called oxidation reaction.
H2 + O2 → H2O
Na + O2 → Na2O
(b) Reduction: When oxygen is removed from a compound, it is called reduction reaction.
H2O2 → H2 + O2
CuO + H2 → Cu + H2O
Q17. 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.
Solution:
The element X is copper (Cu). When copper is heated in air, it forms copper oxide by oxidation which is black in color. Thus the black colored compound formed is copper oxide.
Q18. Why do we apply paint on iron articles?
Solution:
Iron reacts with atmospheric oxygen and moisture and undergoes corrosion to form rust. Painting prevents the surface of iron to come in contact with oxygen and moisture and thus prevents rusting or corrosion of the iron metal.
Q19. Oil and Fat containing food items are flushed with Nitrogen. Why?
Solution:
Oil and fat present in food undergoes oxidation reaction by reacting with oxygen which leads to an unpleasant taste and odour in the food called rancidification. Flushing nitrogen in the food items prevents the reaction of oil and fat with oxygen and maintains the quality of the food and prevents rancidity.
Q20. Explain the following terms with one example each.
(a) Corrosion (b) Rancidity
Solution:
(a) Corrosion: It is a process by which the metals undergo reaction with atmospheric oxides and other compounds in the atmosphere to form their oxides and other compounds which cause degradation of the metal. For example, rusting of iron, copper vessels turning green
(b) Rancidity: The condition when the food containing oil and fat reacts with atmospheric oxygen to produce an unpleasant taste and odor is called rancidity. It renders the food unfit for consumption.
Important Points to Remember
- NCERT solutions are created by a team of professionals a GfG, with the intention to benefit students.
- These solutions are very accurate and comprehensive, which can help students prepare for any academic as well as competitive exam.
- All the solutions provided are in a step-by-step format for better understanding.
Class 10 Chemistry Chapter 1 Chemical Reactions and Equations: FAQs
1. What is Oxidation?
The addition of oxygen to a compound or element is called oxidation.
2. What is Reduction?
The removal of oxygen from a compound or an element is called reduction.
3. Which Gas is used to Prevent Rancidity?
Nitrogen is used to prevent rancidity.
4. What is the Result of the Reaction of an Acid with Base?
When an acid reacts with a base, it form salt and water.
5. What is a Double Displacement Reaction?
A reaction in which two elements displace each other from their compounds to form new compounds is called a double displacement reaction.
6. What will be the result of the following reaction?
ZnSO4 + Cu →
The above reaction will not take place because Copper (Cu) is less reactive than Zinc (Zn) and will not replace it from its compound.
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