Science and Technology I · Textbook solutions

Chemical Reactions and Equations

Every solved example, exercise, and miscellaneous question, in the order the textbook teaches them. Plus every board question asked from this chapter. · 31 questions

Exercise

31 q

Choose the correct option from the bracket and explain the statement giving reason. (Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
Ex Q1(a) $To prevent rusting, a layer of ........ metal is applied on iron sheets.$
Ex Q1(b) $The conversion of ferrous sulphate to ferric sulphate is ........ reaction.$
Ex Q1(c) $When electric current is passed through acidulated water ........ of water takes place.$
Ex Q1(d) $\text{ZnSO}_4$
Write answers to the following.
Ex Q2(a) $What is the reaction called when oxidation and reduction take place simultaneously? Explain with one example.$
Ex Q2(b) $How can the rate of the chemical reaction, namely, decomposition of hydrogen peroxide be increased?$
Ex Q2(c) $Explain the term reactant and product giving examples.$
Ex Q2(d) $Explain the types of reaction with reference to oxygen and hydrogen. Illustrate with examples.$
Ex Q2(e) $Explain the similarity and difference in two events, namely adding NaOH to water and adding CaO to water.$
Explain the following terms with examples.
Ex Q3(a) $Endothermic reaction$
Ex Q3(b) $Combination reaction$
Ex Q3(c) $Balanced equation$
Ex Q3(d) $Displacement reaction$
Give scientific reasons.
Ex Q4(a) $When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky.$
Ex Q4(b) $It takes time for pieces of Shahabad tile to disappear in HCl, but its powder disappears rapidly.$
Ex Q4(c) $While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring.$
Ex Q4(d) $It is recommended to use air tight container for storing oil for long time.$
Ex Q5 $Observe the following picture a write down the chemical reaction with explanation.$
Identify from the following reactions the reactants that undergo oxidation and reduction.
Ex Q6(a) $\text{Fe} + \text{S} \rightarrow \text{FeS}$
Ex Q6(b) $2\text{Ag}_2\text{O} \rightarrow 4\,\text{Ag} + \text{O}_2\uparrow$
Ex Q6(c) $2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$
Ex Q6(d) $\text{NiO} + \text{H}_2 \rightarrow \text{Ni} + \text{H}_2\text{O}$
Balance the following equation stepwise.
Ex Q7(a) $\text{H}_2\text{S}_2\text{O}_7(l) + \text{H}_2\text{O}(l) \rightarrow \text{H}_2\text{SO}_4(l)$
Ex Q7(b) $\text{SO}_2(g) + \text{H}_2\text{S}(aq) \rightarrow \text{S}(s) + \text{H}_2\text{O}(l)$
Ex Q7(c) $\text{Ag}(s) + \text{HCl}(aq) \rightarrow \text{AgCl}\downarrow + \text{H}_2\uparrow$
Ex Q7(d) $\text{NaOH}(aq) + \text{H}_2\text{SO}_4(aq) \rightarrow \text{Na}_2\text{SO}_4(aq) + \text{H}_2\text{O}(l)$
Identify the endothermic and exothermic reaction.
Ex Q8(a) $\text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O} + \text{heat}$
Ex Q8(b) $2\text{KClO}_3(s) \xrightarrow{\Delta} 2\text{KCl}(s) + 3\text{O}_2\uparrow$
Ex Q8(c) $\text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{heat}$
Ex Q8(d) $\text{CaCO}_3(s) \xrightarrow{\Delta} \text{CaO}(s) + \text{CO}_2\uparrow$

Ex Q9

\text{BaCl}_2(aq) + \text{ZnSO}_4(aq)

Reactants	Products	Type of chemical reaction
$\text{BaCl}_2(aq) + \text{ZnSO}_4(aq)$	$\text{H}_2\text{CO}_3(aq)$	Displacement
$2\text{AgCl}(s)$	$\text{FeSO}_4(aq) + \text{Cu}(s)$	Combination
$\text{CuSO}_4(aq) + \text{Fe}(s)$	$\text{BaSO}_4\downarrow + \text{ZnCl}_2(aq)$	Decomposition
$\text{H}_2\text{O}(l) + \text{CO}_2(g)$	$2\text{Ag}(s) + \text{Cl}_2(g)$	Double displacement

What the board has asked from this chapter

Questions per paper · 12 papers · 2016 to 2026

June 2026

3 q

Q1(A)(iii) $आम्लयुक्त पाण्यातून विद्युतप्रवाह जाऊ दिल्यास तर पाण्याचे ____ होते. When electric current is passed through acidulated water ______ of water takes place.$
Tap an option to check your answer.
Types of Chemical Reactions
Q1(B)(iv) $सहसंबंध पूर्ण करा : अन्न शिजणे : रासायनिक बदल :: पाण्याचे बाष्पीभवन : ____Complete the co-relation: Cooking of food : Chemical change :: Evaporation of water : ______.$
Physical and Chemical Changes
Q3(iii) $रासायनिक अभिक्रियेच्या दरावर परिणाम करणारे घटक लिहून कोणत्याही एका घटकाचे स्पष्टीकरण लिहा. State the factors affecting the rate of chemical reaction. Explain any one of it.$
Rate of Chemical Reaction

March 2026

4 q

Q1(B)(i) $गटात न बसणारे घटक लिहा : अन्न शिजणे, फळ परिपक्व होणे, दुधाचे दह्यात रूपांतर होणे, बर्फाचे पाण्यात रूपांतर होणे. Find odd man out: Cooking of food, Ripening of fruit, Milk turned into curd, Transformation of ice into water.$
Physical and Chemical Changes
Q2(B)(ii) $फरक स्पष्ट करा : ऑक्सिडीकरण आणि क्षपण. Distinguish between oxidation and reduction.$
Oxidation, Reduction and Corrosion
Q3(ii) $खालील आकृतीचे निरीक्षण करून खालील प्रश्नांची उत्तरे लिहा : (अ) मोठ्या परीक्षानळीत फसफसून येणारा वायू कोणता आहे ? (ब) चुन्याच्या निवळीच्या रंगात काय बदल होतो ? (क) संबंधित रासायनिक समीकरण लिहा. Observe the figure (apparatus in which acetic acid is dropped through a thistle funnel onto sodium carbonate in a big test tube, and the gas evolved is passed through a gas delivery tube into a small test tube containing freshly prepared lime water) and answer the following questions: (a) Which gas is released out as effervescence in the big test tube? (b) What is the colour change in the lime water? (c) Write the related chemical equation.$
Types of Chemical Reactions

Q3(v)

\mathrm{2NaOH + H_2SO_4 \longrightarrow Na_2SO_4 + H_2O}

मूलद्रव्य	अभिक्रियाकारके (डावी बाजू) अणुसंख्या	उत्पादिते (उजवी बाजू) अणुसंख्या
Na	____	2
O	____	____
H	____	____
S	1	____

Elements	Reactants (Left Side) No. of atoms	Products (Right Side) No. of atoms
Na		2
O
H
S	1

Balancing Chemical Equations

July 2025

4 q

Q1(A)(ii) $अणुवरील किंवा आयनावरील धनप्रभार जेव्हा वाढतो किंवा ऋणप्रभार कमी होतो तेव्हा त्याला ____ असे म्हणतात. When the positive charge on an atom or an ion increases or the negative charge on them decreases it is called ____ .$
Tap an option to check your answer.
Oxidation, Reduction and Corrosion
Q2(B)(iii) $\mathrm{CuSO_{4(aq)} + Fe_{(s)} \longrightarrow}$
Types of Chemical Reactions
Q3(iii) $\mathrm{HCl + NaOH \longrightarrow NaCl + H_2O +}$
Types of Chemical Reactions
Q3(viii) $खालील अभिक्रियांसाठी रासायनिक समीकरणे लिहा : (अ) थर्मिट अभिक्रिया (ब) मॅग्नेशिअम फितीचे हवेतील ज्वलन (क) लोखंडाचा खिळा/चुरा कॉपर सल्फेटच्या जलीय द्रावणात टाकला. Give the chemical equations for the following reactions: (a) Thermit reaction (b) Burning of magnesium in air (c) Iron nail/dust is dropped in aqueous solution of copper sulphate.$
Types of Chemical Reactions

March 2025

4 q

Q1(A)(ii) $ज्या अभिक्रियांमध्ये अभिकारकामधील आयनांची अदलाबदल होऊन अवक्षेप तयार होतो अशा अभिक्रियांना ____ असे म्हणतात. The reaction in which ions in the reactants are exchanged to form a precipitate is called as ____ reaction.$
Tap an option to check your answer.
Types of Chemical Reactions
Q1(A)(v) $\mathrm{CaO + H_2O \longrightarrow Ca(OH)_2}$
Tap an option to check your answer.
Types of Chemical Reactions
Q1(B)(i) $चूक की बरोबर ते लिहा : पेशींमधील श्वसनादरम्यान रेडॉक्स अभिक्रिया घडत असते. State whether true or false: A redox reaction takes place during cellular respiration.$
Oxidation, Reduction and Corrosion
Q2(B)(v) $अपघटन अभिक्रिया म्हणजे काय ? साखरेच्या अपघटन अभिक्रियेचे समीकरण लिहा. What is meant by decomposition reaction? Write the chemical reaction of decomposition of sugar on heating.$
Types of Chemical Reactions

July 2024

3 q

Q1(A)(ii) $\mathrm{CuSO_{4(aq)} + Zn_{(s)} \longrightarrow ZnSO_{4(aq)} + Cu_{(s)}}$
Tap an option to check your answer.
Types of Chemical Reactions
Q2(B)(iii) $\mathrm{2H_2S + SO_2 \longrightarrow 3S\downarrow + 2H_2O}$
Oxidation, Reduction and Corrosion
Q3(i) $\mathrm{CaCO_{3(s)} \xrightarrow{\Delta} CaO_{(s)} + CO_2\uparrow}$
Types of Chemical Reactions

March 2024

3 q

Q1(B)(ii) $कॅल्शिअम कार्बोनेटचे रेणूसूत्र लिहा. Write the molecular formula of calcium carbonate.$
Balancing Chemical Equations
Q2(A)(i) $शास्त्रीय कारणे लिहा : चुनखडी तापवून मिळालेला वायू ताज्या चुन्याच्या निवळीतून जाऊ दिल्यास निवळी दुधाळ होते. Give scientific reason: When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky.$
Types of Chemical Reactions
Q3(ii) $(a) रासायनिक अभिक्रियेच्या वेगावर परिणाम करणारे घटक कोणते आहेत ? (b) त्यातील कोणत्याही एका घटकाचे स्पष्टीकरण द्या. (a) What are the factors affecting the rate of chemical reaction? (b) Explain any one factor.$
Rate of Chemical Reaction

March 2023

3 q

Q1(B)(ii) $CuI_2$
Types of Chemical Reactions
Q2(B)(ii) $C_{12}H_{22}O_{11} \xrightarrow{\text{heat}}$
Types of Chemical Reactions
Q3(v) $Identify the physical and chemical changes from the following phenomena: (a) Transformation of ice into water. (b) Ripening of fruit. (c) Milk turned into curd. (d) Evaporation of water. (e) Digestion of food in the stomach. (f) Iron filings get attracted towards the magnet.$
Physical and Chemical Changes

March 2022

3 q

Identify the type of chemical reaction given below:
Q3(iii)(a) $\mathrm{CuSO_4 + Fe \rightarrow FeSO_4 + Cu}$
Types of Chemical Reactions
Q3(iii)(b) $\mathrm{2Mg + O_2 \rightarrow 2MgO}$
Types of Chemical Reactions
Q3(iii)(c) $\mathrm{2KClO_3 \rightarrow 2KCl + 3O_2 \uparrow}$
Types of Chemical Reactions

March 2020

1 q

Q2(B)(iv) $\mathrm{CuSO_4\,(aq) + Fe\,(s) \rightarrow \underline{\qquad} + \underline{\qquad}}$
Displacement Reaction

March 2019

4 q

Q1(B)(1) $The reaction of iron nail with copper sulphate solution is ________ reaction.$
Tap an option to check your answer.
Types of Chemical Reactions
Study the following chemical reaction and answer the questions given below: $\mathrm{AgNO_{3(aq)} + NaCl_{(aq)} \rightarrow AgCl_{(s)}\!\downarrow + NaNO_{3(aq)}}$
Q3(3)(i) $Identify and write the type of chemical reaction.$
Types of Chemical Reactions
Q3(3)(ii) $Write the definition of the above type of chemical reaction.$
Types of Chemical Reactions
Q3(3)(iii) $Write the names of the reactants and products of the above reaction.$
Types of Chemical Reactions

March 2018

3 q

Q1(A)(c) $\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$
Types of Chemical Reactions
Q1(B)(1) $When crystals of copper sulphate are strongly heated, the residue obtained is ______.$
Tap an option to check your answer.
Types of Chemical Reactions
Q3(2) $What is a redox reaction? Explain with one example.$
Oxidation, Reduction and Corrosion

March 2016

2 q

Q1(B)(1) $Reaction of iron nails with copper sulphate solution is an example of$
Tap an option to check your answer.
Types of Chemical Reactions
Q3(2) $Define 'redox reaction'. Give one example.$
Oxidation, Reduction and Corrosion

The 10 board questions to practise first

The questions the board asked again come first, most asked first. Each one says how often and when.

Question 1
Asked 2 times: Mar 2024, Jun 2026
Q3(iii) $रासायनिक अभिक्रियेच्या दरावर परिणाम करणारे घटक लिहून कोणत्याही एका घटकाचे स्पष्टीकरण लिहा. State the factors affecting the rate of chemical reaction. Explain any one of it.$
Question 2
Asked 2 times: Mar 2024, Mar 2026* (* = numbers or wording changed that year)
Q3(ii) $खालील आकृतीचे निरीक्षण करून खालील प्रश्नांची उत्तरे लिहा : (अ) मोठ्या परीक्षानळीत फसफसून येणारा वायू कोणता आहे ? (ब) चुन्याच्या निवळीच्या रंगात काय बदल होतो ? (क) संबंधित रासायनिक समीकरण लिहा. Observe the figure (apparatus in which acetic acid is dropped through a thistle funnel onto sodium carbonate in a big test tube, and the gas evolved is passed through a gas delivery tube into a small test tube containing freshly prepared lime water) and answer the following questions: (a) Which gas is released out as effervescence in the big test tube? (b) What is the colour change in the lime water? (c) Write the related chemical equation.$
Question 3
Asked 2 times: Mar 2020, Jul 2025* (* = numbers or wording changed that year)
Q2(B)(iii) $\mathrm{CuSO_{4(aq)} + Fe_{(s)} \longrightarrow}$
Question 4
Asked 2 times: Mar 2023, Mar 2025* (* = numbers or wording changed that year)
Q2(B)(v) $अपघटन अभिक्रिया म्हणजे काय ? साखरेच्या अपघटन अभिक्रियेचे समीकरण लिहा. What is meant by decomposition reaction? Write the chemical reaction of decomposition of sugar on heating.$
Question 5
Asked 2 times: Mar 2016, Mar 2019
Q1(B)(1) $The reaction of iron nail with copper sulphate solution is ________ reaction.$
Tap an option to check your answer.
Question 6
Asked 2 times: Mar 2016, Mar 2018
Q3(2) $What is a redox reaction? Explain with one example.$
Question 7
This type asked 6 times: Mar 2016, Mar 2018, Mar 2019, Mar 2022, Jul 2024, Mar 2025. This one: Mar 2025
Q1(A)(ii) $ज्या अभिक्रियांमध्ये अभिकारकामधील आयनांची अदलाबदल होऊन अवक्षेप तयार होतो अशा अभिक्रियांना ____ असे म्हणतात. The reaction in which ions in the reactants are exchanged to form a precipitate is called as ____ reaction.$
Tap an option to check your answer.
Question 8
This type asked 5 times: Mar 2018, Mar 2023, Mar 2024, Jul 2024, Jun 2026. This one: Jun 2026
Q1(A)(iii) $आम्लयुक्त पाण्यातून विद्युतप्रवाह जाऊ दिल्यास तर पाण्याचे ____ होते. When electric current is passed through acidulated water ______ of water takes place.$
Tap an option to check your answer.
Question 9
This type asked 5 times: Mar 2016, Jul 2024, Mar 2025, Jul 2025, Mar 2026. This one: Mar 2026
Q2(B)(ii) $फरक स्पष्ट करा : ऑक्सिडीकरण आणि क्षपण. Distinguish between oxidation and reduction.$
Question 10
This type asked 3 times: Mar 2023, Mar 2026, Jun 2026. This one: Jun 2026
Q1(B)(iv) $सहसंबंध पूर्ण करा : अन्न शिजणे : रासायनिक बदल :: पाण्याचे बाष्पीभवन : ____Complete the co-relation: Cooking of food : Chemical change :: Evaporation of water : ______.$

Exercise

What the board has asked from this chapter

June 2026

March 2026

July 2025

March 2025

July 2024

March 2024

March 2023

March 2022

March 2020

March 2019

March 2018

March 2016

The 10 board questions to practise first

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10