# Ncert Science Class 10 Solutions Chapter 1

## Ncert Science Class 10 Solutions Chapter 1 Chemical Reactions and Equations

Welcome to NCTB Solutions. Here with this post we are going to help 10th class students for the Solutions of NCERT Class 10 Science Book Chapter 1, Chemical Reactions and Equations. Here students can easily find step by step solutions of all the questions in Chemical Reactions and Equations. Also our Expert Science Teacher’s solved all the problems with easily understandable language with proper guidance so that all the students can understand easily. Here in this post students will get chapter 1 solutions. Here all Question Answer are based on NCERT latest syllabus.

Chemical Reactions and Equations Exercise question Solutions :

(1) Which of the statements about the reaction below are incorrect? 2PbO(s) + C(s) → 2Pb(s) + CO2(g)

The correct option – (i) (a) and (b)

(b) Carbon dioxide is getting oxidised.

(2) Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a

The correct option is  – (d)

The above reaction is an example of a displacement reaction.

(3) What happens when dilute hydrochloric acid is added to iron fillings?

The answer is option – (a)

Hydrogen gas and iron chloride are produced.

(4) What is a balanced chemical equation? Why should chemical equations be balanced?

A balanced chemical equation is the equation in which number of atoms of each element is equal in both reaction and products side. In every reaction there is amount of mass of element present which are reactants from the law of mass can not be created nor destroyed means, The reactant after reaction becomes product of same amount of mass physically.

So, Total mass of element in reactant and product side should be written equally.

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

(a) Hydrogen gas combines with nitrogen to form ammonia.

Chemical Equation = N2 + H2 → NH3

Balance = N2 + 3H2 → 2[NH3]

(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide

Chemical Equation = H2S + O2 → SO2 + H2O

Balance = 2H2S +3O2 → 2SO2 + 2H2O

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

Chemical Equation = BaCl2 + Al2 [SO4]3 → AlCl3 + BaSO4

Balance = 3BaCl2 + Al2 [SO4]3 → 2AlCl3 + 3BaSO4

(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen Gas

Chemical Equation = K + H2O → KOH + H2

Balance = 2K + 2H2O → 2KOH + H2

(6) Balance the following chemical equations

(a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O

= 2HNO3 + Ca[OH]2 → Ca[NO3]2 + H2O

(b) NaOH + H2SO4 → Na2SO4+ H2O

= 2[NAOH] + H2SO4 → Na2SO4 + 2H2O

(c) NaCl + AgNO3 → AgCl + NaNO3

= NaCl + AgNO3 → AgCl + NaNO3

(d) BaCl2 + H2SO4 → BaSO4 + HCl

= BaCl2 + H2SO4 → BaSO4+2HCl

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

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

= 2[CaOH] + CO2 → Ca2CO3 + H2O

(b) Zinc + Silver nitrate → Zinc nitrate + Silver

= Zn +AgNO3 → Zn NO3 + Ag

(c) Aluminium + Copper chloride → Aluminium chloride + Copper

= Al + CuCl2 → Alcl2 + Cu

(d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride

= BaCl2 + KSO4 → BaSO4 + Kcl2

(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)

= Br + BaI2 → KI + BaBr2

= Double displacement Reaction

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

= ZnCO3 → ZnO + CO2

= Decomposition Reaction

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

= H2 + Cl2 → 2HCl

= Combination Reaction

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

= Mg + 2HCl → MgCl2 + H2

= Displacement Reaction

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

Exothermic and endothermic reactions means –

Reaction in which heat is released along with the formation of products is called exothermic chemical reaction.

i.e. burning of natural gas

CH4 [g] + 2O2 [g] → CO2 [g] + 2H2O [g]

Methane Oxygen Carbone dioxide Water

In this reaction large amount of heat is extracted. Which make this reaction warm.

Reaction in which energy is absorbed are known as endothermic reactions.

i.e. 2AgBr [s] → 2Ag[s] + Br2 [g]

Silver Bromide silver Bromine

In above reaction decomposition takes energy by sunlight. Mostly decomposition reactions take energy in the form of heat, sunlight or electricity.

(10) Why is respiration considered an exothermic reaction? Explain.

Respiration considered an exothermic reaction because –

C6H12O6 [aq] + 6O2 [aq] → 6CO2 + 6H2O [l]

Glucose Oxygen Carbon dioxide Water

The above reaction is decomposition type of reaction. we know that work require energy. Our body does regular activity like respiration, digestion, movement, excretion, sleeping, eating. we get this energy from food we eat.

Firstly, food is digested into carbohydrates, protein, fat then this substance further break down into glucose and lastly glucose reacts with oxygen we inhale to form energy and water (Urine) and carbon dioxide we exhale.

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

Decomposition reactions called the opposite of combination reactions because –

C [s] + O2 [g] → CO2 [g] + heat

Carbon Oxygen Carbon Dioxide

Reaction in which single product is formed from two or more reactants is known as combination reaction. Combination reaction release heat(energy) and they are exothermic.

CaCO3 [s] → CaO [s] + CO2 [g]

Limestone quick lime Carbon Dioxide

Reaction in which single reactant break down to give simpler products called as decomposition reaction. Decomposition reaction absorbs energy and they are endothermic.

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Updated: June 30, 2023 — 7:19 am