NCERT Solutions for Class 10 Science Chapter 1 – Chemical Reactions and Equations provide simple and accurate answers to all textbook questions. These solutions help students understand chemical reactions, balanced equations, and different types of reactions in an easy and effective way. Prepared according to the latest NCERT syllabus, they are useful for exam preparation and concept clarity.
NCERT TEXT-BOOK EXERCISE SOLUTION
Page No. :- 14 - 16
Ques 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 |
Ans:- (i) (a) and (b).
Reason :- In the given reaction PbO has lost oxygen to form Pb, therefore lead oxide is getting reduced.
Carbon (C) has gained oxygen to form CO2, therefore carbon is getting oxidised.
Ques 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
Ans :- (d) displacement reaction
Reason :- In this reaction, aluminium (Al) displaces iron (Fe) from iron oxide (Fe2O3) to form aluminium oxide (Al2O3) and iron (Fe). Therefore, it is a displacement reaction.
Ques 3 :- 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.
Ans:- (a) Hydrogen gas and iron chloride are produced.
The following reaction takes place :-
Fe + 2HCl --------> FeCl2 + H2
Reason :- Iron (Fe) reacts with dilute hydrochloric acid (HCl) to form iron chloride (FeCl2) and hydrogen gas (H2). Therefore, hydrogen gas and iron chloride are produced.
Ques 4 :- What is a balanced chemical equation ? Why should chemical equations be balanced ?
Ans:- Balanced Chemical Equation :- A chemical equation is said to be balanced if :
(i) the atoms of different elements on both sides of the equation are equal.
(ii) the equation is molecular, i.e., the gases involved in the equation must be in the molecular form
(e.g., H2, O2, N2, Cl2 etc.)
Necessity to balance chemical equations :-
The chemical equations are balanced to satisfy the Law of Conservation of Mass in a chemical reaction since matter can neither be created nor be destroyed in a chemical reaction.
Ques 5:- Translate the following statements into chemical equations and then balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
Ans:-
(a) H2(g) + N2(g) ---------> NH3(g)
3H2(g) + N2(g) ---------> 2NH3(g)
(b) Hydrogen sulphide gas burns in air to give water and Sulphur dioxide.
Ans:-
(b) H2S(g) + O2(g) ---------> SO2 + H2O
2H2S(g) + 3O2(g) ---------> 2SO2 + 2H2O
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
Ans:-
(c) BaCl2(aq) + Al2(SO4)3(aq) ---------> AlCl3(aq) + BaSO4
3BaCl2(aq) + Al2(SO4)3(aq) ---------> 2AlCl3(aq) + 3BaSO4
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
Ans:-
(d) K(s) + H2O ------> KOH + H2
2K(s) + 2H2O ------> 2KOH + H2
Ques 6:- Balance the following chemical equations :
(a) HNO3 + Ca(OH)2 ---------> Ca(NO3)2 + H2O
Ans:-
2HNO3 + Ca(OH)2 ---------> Ca(NO3)2 + 2H2O
(b) NaOH + H2SO4 ------> Na2SO4 + H2O
Ans:-
2NaOH + H2SO4 ------> Na2SO4 + 2H2O
(c) NaCl + AgNO3 ------> AgCl + NaNO3
Ans:-
NaCl + AgNO3 ------> AgCl + NaNO3
(d) BaCl2 + H2SO4 ------> BaSO4 + HCl
Ans:-
BaCl2 + H2SO4 ------> BaSO4 + 2HCl
Q. 7. Write the balanced Chemical Equation for the following reaction.
(a) Calcium hydroxide + Carbon dioxide ------> Calcium carbonate + Water
Ans:-
Ca(OH)2 + CO2 ------> CaCO3 + H2O
(b) Zinc + Silver nitrate ------> Zinc nitrate + Silver
Ans:-
Zn + 2AgNO3 ------> Zn(NO3)2 + 2Ag
(C) Aluminium + Copper chloride ------> Aluminium chloride + Copper
Ans:-
2Al + 3CuCl2 ------> 2AlCl3 + 3Cu
(d) Barium chloride + Potassium sulphate ------> Barium sulphate + Potassium chloride
Ans:-
BaCl2 + K2SO4 ------> BaSO4 + 2KCl
Ques 8:- Write the balanced chemical equation for the following and identified the type of reaction in each case :-
(a) Potassium bromide(aq) + Barium iodide(aq) ----> Potassium iodide(aq) + Barium bromide(s).
Ans:-
2KBr(aq) + BaI2(aq) ------> 2KI(aq) + BaBr2(aq)
(Double displacement reaction)
(b) Zinc carbonate (s) ------> Zinc oxide(s) + Carbon dioxide(g).
Ans:-
ZnCO3 ---------> ZnO(s) + CO2(g)
(Decomposition Reaction)
(c) Hydrogen (g) + Chloride (g) ------> Hydrogen chloride (g).
Ans:-
H2 (g) + Cl2 (g) ---------> 2HCl (g)
(Combination reaction)
(c) Hydrogen (g) + Chloride (g) ------> Hydrogen chloride (g).
Ans:-
H2 (g) + Cl2 (g) ---------> 2HCl (g)
(Combination reaction)
(d) Magnesium (s) + Hydrochloric acid(aq) ------> Magnesium chloride(aq) + Hydrogen (g)
Ans:-
Mg (s) + 2HCl (aq) ---------> MgCl 2(aq) + H 2 (g)
(Displacement reaction).
Ques 9:- What does one mean by exothermic and endothermic reactions ? Give examples.
Ans:- A chemical reaction is said to be exothermic reaction in which a certain amount of heat energy is released. The container in which the reaction takes place becomes hot.
For example :
N2(g) + 3H2(g) ---------> 2NH3(g) + 92 kJ
CH4(g) + 2O2(g) ---------> CO2(g) + 2H2O(l) + 890 kJ
NaOH(aq) + HCl(aq) ---------> NaCl(aq) + H2O(l) + 57.5 kJ
Ans:- A chemical reaction is said to be endothermic reaction in which a certain amount of heat energy is absorbed. The container in which the reaction takes place becomes cold.
For example :
N2(g) + O2(g) ---------> 2NO(g) - 180 kJ
C(s) + H2O(g) ---------> CO(g) + H2(g) - 130 kJ
2NH3(g) ---------> N2(g) + 3H2(g) - 46.4 kJ
Ques 10:- Why is the respiration considered an exothermic reaction ? Explain.
Ans: Respiration is considered an exothermic reaction because during respiration, glucose produced by the digestion of food combines with oxygen in the cells of our body to produce carbon dioxide, water and heat energy.
C6H12O6 + 6O2(g) ---------> 6CO2 + 6H2O(l) + 2820 kJ
(Glucose)
Ques 11 :- Why are decomposition reaction Called the opposite of combination, reactions? Write equations for these reactions.
Ans: In a decomposition reaction, one substance (compound) splits to give two or more simpler substances (elements or compounds).
Whereas, in a combination reaction, two or more substances (elements or compounds) combine to form a single substance. Therefore, a decomposition reaction is called the opposite of a combination reaction.
Examples of Decomposition Reactions :-
(i) CaCO3 (s) (Heat) ⟶ CaO (s) + CO2 (g)
(ii)2FeSO4 (s) (Heat) ⟶ Fe2O3 (s) + SO2 (g) + SO3 (g)
Examples of Combination Reactions :-
(i) CaO (s) + CO2 (g) ⟶ CaCO3 (s)
(ii) 2H2 (g) + O2 (g) ⟶ 2H2O (l)
Ques 12:- Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
Ans:- (i) Decomposition reaction involving absorption of heat.
2KClO3 (s) (Heat) ---------> 2KCl (s) + 3O2 (g)
(ii) Decomposition reaction involving absorption of Light.
2AgCl (s) (Sunlight) ---------> 2Ag (s) + Cl2 (g)
(iii) Decomposition reaction involving absorption of electricity.
2H2O (l) (electricity) ---------> 2H2 (g) + O2 (g)
Ques 13:- What is the difference between displacement and double displacement reactions? Write equations for these reactions.
Ans: Displacement reactions :- In a displacement reaction, a more reactive element displaces a less reactive element from its salt solution.
Examples :
(i) CuSO4(aq) + Fe(s) ------> FeSO4(aq) + Cu(s)
(ii) CuSO4(aq) + Zn(s) ------> ZnSO4(aq) + Cu(s)
Double displacement reactions : In double displacement reactions, two compounds exchange their ions to form new compounds.
Examples :-
(i) AgNO3(aq) + NaCl(aq) ------> AgCl(s) + NaNO3(aq)
(ii) 2AgNO3(aq) + CuCl2(aq) ------> 2AgCl(s) + Cu(NO3)2(aq)
Ques 14:- In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal.Write down the reaction involved.
Ans:
2AgNO3(aq) + Cu(s) ---------> Cu(NO3)2(aq) + 2Ag(s)
Ques 15 :- What do you mean by a precipitation reaction? Explain by giving examples.
Ans: In a precipitation reaction, one of the products formed during the reaction is an insoluble solid substance which separates from the solution. This insoluble solid is called a precipitate.
For example:-
AgNO3(aq) + NaCl(aq) ---------> AgCl(s) + NaNO3(aq)
(white ppt.)
BaCl2(aq) + Na2SO4(aq) ---------> BaSO4(s) + 2NaCl(aq)
(white ppt.)
Ques 16:- Explain the following in terms of gain or loss of oxygen with two examples each :-
(a) Oxidation
(b) Reduction
(a) Oxidation :- Any process which involves addition of oxygen is called oxidation.
Examples :-
(i) Burning of carbon in the presence of oxygen.
C(s) + O2(g) ---------> CO2(g)
(ii) Burning of magnesium in the presence of oxygen.
2Mg(s) + O2(g) ---------> 2MgO(s)
(b) Reduction :- Any process which involves removal of oxygen is called reduction.
Examples :-
CuO(s) + H2 ---------> Cu(s) + H2O(l)
ZnO(s) + C(s) ---------> Zn(s) + CO(g)
Ques 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.
Ans:- The element 'X' is copper and the black coloured compound formed is copper(II) oxide.
Ques 18:- Why do we apply paint on iron articles ?
Ans:- Paint forms a protective coating on the surface of iron. It prevents air and moisture from coming in direct contact with iron. Therefore, the iron surface is protected from rusting.
Ques 19:- Oil and fat containing food items are flushed with nitrogen. Why ?
Ans:- Oil and fat containing food items become rancid due to oxidation by air or oxygen. When the food packets are flushed with nitrogen, oxygen is removed and oxidation is prevented. Therefore, rancidity is checked.
Ques 20:- Explain the following terms with one example each.
(a) Corrosion (b) Rancidity
(a) Corrosion :- Corrosion is the process in which metals are slowly damaged by air, moisture or chemicals.
Example: Rusting of iron.
(b) Rancidity :- Rancidity is the process in which oils and fats get oxidised and develop an unpleasant smell and taste.
Example: Chips or oily food items becoming stale after a long time.
NCERT Solutions for Class 10 Science Chapter 1 – Chemical Reactions and Equations provide simple and accurate answers to all textbook questions. These solutions help students understand chemical reactions, balanced equations, and different types of reactions in an easy and effective way. Prepared according to the latest NCERT syllabus, they are useful for exam preparation and concept clarity.
Frequently Asked Questions (FAQs)
Q1. What is a chemical reaction?
A chemical reaction is a process in which one or more substances are converted into new substances with different properties.
Q2. What is a chemical equation?
A chemical equation is a symbolic representation of a chemical reaction using the chemical formulas of reactants and products.
Q3. Why should a chemical equation be balanced?
A chemical equation should be balanced to satisfy the law of conservation of mass, which states that matter can neither be created nor destroyed.
Q4. What are the main types of chemical reactions?
The main types of chemical reactions are combination, decomposition, displacement, double displacement, oxidation, and reduction reactions.
Q5. How do NCERT Solutions help students?
NCERT Solutions help students understand concepts clearly, improve problem-solving skills, and prepare effectively for school and board examinations.
0 Comments
Please do not enter any spam link in the comment box.