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Chemical Reactions and Equations quiz

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Question 1

Evidence of reaction

Difficulty: EasySource: NCERT Chapter 1, opening observations after Activities 1.1-1.3Topic: chemical-equations

Which observation is listed by NCERT as evidence that a chemical reaction may have occurred?

1evolution of a gas2change in the size of a container3movement of a test tube4change in handwriting

Question 2

Figure 1.2

Difficulty: EasySource: NCERT Activity 1.3 and Figure 1.2Topic: chemical-equations

NCERT Figure 1.2 belongs to which activity?

1lead nitrate mixed with potassium iodide2zinc reacting with dilute sulphuric acid3quicklime mixed with water4iron nails dipped in copper sulphate

Question 3

Skeletal equation

Difficulty: EasySource: NCERT Section 1.1.1, equation (1.2)Topic: chemical-equations

Why is Mg + O₂ → MgO called a skeletal equation?

1It contains no element symbols.2It contains no reactants.3Its atom counts are not equal on the two sides.4It describes only a physical change.

Question 4

Conservation of mass

Difficulty: EasySource: NCERT Section 1.1.2, balanced chemical equationsTopic: balancing-equations

Why must a chemical equation be balanced?

1To make every formula shorter2To remove physical-state symbols3To change products into reactants4To obey the law of conservation of mass

Question 5

Steam symbol

Difficulty: EasySource: NCERT equation (1.10)Topic: balancing-equations

In equation (1.10), why is water written as H₂O(g)?

1Water is used as steam.2Water is dissolved in another liquid.3Water is frozen.4Water is acting as a catalyst.

Question 6

Combination pattern

Difficulty: EasySource: NCERT Section 1.2.1, combination reactionTopic: combination-and-decomposition-reactions

Which pattern defines a combination reaction?

1One reactant always forms one element.2Two or more reactants form a single product.3Two compounds exchange ions.4One element replaces another.

Question 7

Balancing sodium and water

Difficulty: MediumSource: NCERT first Questions block, Question 2(iii)Topic: balancing-equations

Which is the correctly balanced equation for sodium reacting with water?

1Na + H₂O → NaOH + H₂22Na + H₂O → 2NaOH + H₂32Na + 2H₂O → 2NaOH + H₂4Na + 2H₂O → NaOH + 2H₂

Question 8

Reaction condition

Difficulty: MediumSource: NCERT equation (1.11)Topic: balancing-equations

Which condition is shown for the formation of methanol in equation (1.11)?

1sunlight2electricity3chlorophyll4340 atm pressure

Question 9

Whitewashing

Difficulty: MediumSource: NCERT Do You Know box and equation (1.14)Topic: combination-and-decomposition-reactions

Which substance gives a shiny finish to a whitewashed wall after two to three days?

1calcium carbonate2calcium oxide3carbon monoxide4calcium chloride

Question 10

Ferrous sulphate

Difficulty: MediumSource: NCERT Activity 1.5 and equation (1.19)Topic: combination-and-decomposition-reactions

What happens before ferrous sulphate decomposes into ferric oxide and sulphur oxides?

1It gains chlorine.2Its hydrated crystals lose water.3It forms a silver precipitate.4It absorbs carbon dioxide.

Question 11

Electrolysis volumes

Difficulty: MediumSource: NCERT Activity 1.7 and second Questions block, Question 2Topic: combination-and-decomposition-reactions

Which gas is collected in approximately double the volume during electrolysis of water?

1oxygen2chlorine3hydrogen4nitrogen dioxide

Question 12

Photography reaction

Difficulty: MediumSource: NCERT Activity 1.8 and equations (1.22)-(1.23)Topic: combination-and-decomposition-reactions

Why do silver chloride and silver bromide turn grey in sunlight?

1They dissolve in water.2They combine with nitrogen.3They form carbon dioxide.4Light decomposes them and silver metal forms.

Question 13

Displacement observation

Difficulty: MediumSource: NCERT Activity 1.9 and equation (1.24)Topic: displacement-and-double-displacement-reactions

Why does the blue colour of copper sulphate solution fade when iron nails are immersed?

1Iron displaces copper and pale-green iron sulphate forms.2Copper sulphate evaporates completely.3Iron changes into lead.4The solution becomes pure water.

Question 14

Precipitation

Difficulty: MediumSource: NCERT Activity 1.10 and equation (1.27)Topic: displacement-and-double-displacement-reactions

What is the white precipitate in Activity 1.10?

1sodium chloride2barium sulphate3iron sulphate4potassium nitrate

Question 15

Redox identification

Difficulty: MediumSource: NCERT equation (1.29)Topic: oxidation-and-reduction

In CuO + H₂ → Cu + H₂O, which statement is correct?

1CuO is oxidised and H₂ is reduced.2Both CuO and H₂ are oxidised.3H₂ is oxidised and CuO is reduced.4Neither reactant changes.

Question 16

Corrosion near the sea

Difficulty: HardSource: Platform application - NCERT Section 1.3.1 CorrosionTopic: oxidation-and-reduction

An unpainted iron gate near the sea develops a reddish-brown coating faster than a similar gate in a dry area. Which explanation and prevention pair is correct?

1Salt converts iron directly into paint; washing with more salt prevents it.2Only sunlight causes the coating; keeping the gate wet prevents it.3Nitrogen in air forms rust; scratching the surface prevents it.4Moisture and oxygen promote corrosion; painting the gate creates a protective barrier.

Question 17

Decomposition numbering

Difficulty: HardSource: NCERT equations (1.20)-(1.23)Topic: combination-and-decomposition-reactions

Which statement about the NCERT equation sequence is correct?

1(1.20) is calcium carbonate decomposition and (1.21) is lead nitrate decomposition.2(1.20) is electrolysis of water and (1.21) is silver chloride decomposition.3The electrolysis equation is numbered (1.21).4Silver bromide decomposition is numbered (1.22).

Question 18

Two-reaction classification

Difficulty: HardSource: NCERT Sections 1.2.3-1.2.4Topic: displacement-and-double-displacement-reactions

How should these reactions be classified in order? Zn + CuSO₄ → ZnSO₄ + Cu; Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

1combination, decomposition2displacement, double displacement3double displacement, displacement4oxidation only, combination

Question 19

Complete oxidation answer

Difficulty: HardSource: NCERT Exercise 16Topic: oxidation-and-reduction

Which pair correctly gives two examples of oxidation by gain of oxygen?

1CuO → Cu and PbO → Pb2AgCl → Ag and CaCO₃ → CaO32Mg + O₂ → 2MgO and 2Cu + O₂ → 2CuO4H₂O → H₂ and FeSO₄ → Fe₂O₃

Question 20

Rancidity reasoning

Difficulty: HardSource: NCERT Section 1.3.2 and Exercise 19Topic: ncert-exercises-and-revision

Why are oily food packets flushed with nitrogen?

1Nitrogen changes oil into water.2Nitrogen increases the packet temperature.3Nitrogen makes oxidation faster.4Nitrogen limits contact with oxygen and delays rancidity.

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Question 1

Evidence of reaction

Difficulty: EasySource: NCERT Chapter 1, opening observations after Activities 1.1-1.3Topic: chemical-equations

Which observation is listed by NCERT as evidence that a chemical reaction may have occurred?

1evolution of a gas2change in the size of a container3movement of a test tube4change in handwriting

Question 2

Figure 1.2

Difficulty: EasySource: NCERT Activity 1.3 and Figure 1.2Topic: chemical-equations

NCERT Figure 1.2 belongs to which activity?

1lead nitrate mixed with potassium iodide2zinc reacting with dilute sulphuric acid3quicklime mixed with water4iron nails dipped in copper sulphate

Question 3

Skeletal equation

Difficulty: EasySource: NCERT Section 1.1.1, equation (1.2)Topic: chemical-equations

Why is Mg + O₂ → MgO called a skeletal equation?

1It contains no element symbols.2It contains no reactants.3Its atom counts are not equal on the two sides.4It describes only a physical change.

Question 4

Conservation of mass

Difficulty: EasySource: NCERT Section 1.1.2, balanced chemical equationsTopic: balancing-equations

Why must a chemical equation be balanced?

1To make every formula shorter2To remove physical-state symbols3To change products into reactants4To obey the law of conservation of mass

Question 5

Steam symbol

Difficulty: EasySource: NCERT equation (1.10)Topic: balancing-equations

In equation (1.10), why is water written as H₂O(g)?

1Water is used as steam.2Water is dissolved in another liquid.3Water is frozen.4Water is acting as a catalyst.

Question 6

Combination pattern

Difficulty: EasySource: NCERT Section 1.2.1, combination reactionTopic: combination-and-decomposition-reactions

Which pattern defines a combination reaction?

1One reactant always forms one element.2Two or more reactants form a single product.3Two compounds exchange ions.4One element replaces another.

Question 7

Balancing sodium and water

Difficulty: MediumSource: NCERT first Questions block, Question 2(iii)Topic: balancing-equations

Which is the correctly balanced equation for sodium reacting with water?

1Na + H₂O → NaOH + H₂22Na + H₂O → 2NaOH + H₂32Na + 2H₂O → 2NaOH + H₂4Na + 2H₂O → NaOH + 2H₂

Question 8

Reaction condition

Difficulty: MediumSource: NCERT equation (1.11)Topic: balancing-equations

Which condition is shown for the formation of methanol in equation (1.11)?

1sunlight2electricity3chlorophyll4340 atm pressure

Question 9

Whitewashing

Difficulty: MediumSource: NCERT Do You Know box and equation (1.14)Topic: combination-and-decomposition-reactions

Which substance gives a shiny finish to a whitewashed wall after two to three days?

1calcium carbonate2calcium oxide3carbon monoxide4calcium chloride

Question 10

Ferrous sulphate

Difficulty: MediumSource: NCERT Activity 1.5 and equation (1.19)Topic: combination-and-decomposition-reactions

What happens before ferrous sulphate decomposes into ferric oxide and sulphur oxides?

1It gains chlorine.2Its hydrated crystals lose water.3It forms a silver precipitate.4It absorbs carbon dioxide.

Question 11

Electrolysis volumes

Difficulty: MediumSource: NCERT Activity 1.7 and second Questions block, Question 2Topic: combination-and-decomposition-reactions

Which gas is collected in approximately double the volume during electrolysis of water?

1oxygen2chlorine3hydrogen4nitrogen dioxide

Question 12

Photography reaction

Difficulty: MediumSource: NCERT Activity 1.8 and equations (1.22)-(1.23)Topic: combination-and-decomposition-reactions

Why do silver chloride and silver bromide turn grey in sunlight?

1They dissolve in water.2They combine with nitrogen.3They form carbon dioxide.4Light decomposes them and silver metal forms.

Question 13

Displacement observation

Difficulty: MediumSource: NCERT Activity 1.9 and equation (1.24)Topic: displacement-and-double-displacement-reactions

Why does the blue colour of copper sulphate solution fade when iron nails are immersed?

1Iron displaces copper and pale-green iron sulphate forms.2Copper sulphate evaporates completely.3Iron changes into lead.4The solution becomes pure water.

Question 14

Precipitation

Difficulty: MediumSource: NCERT Activity 1.10 and equation (1.27)Topic: displacement-and-double-displacement-reactions

What is the white precipitate in Activity 1.10?

1sodium chloride2barium sulphate3iron sulphate4potassium nitrate

Question 15

Redox identification

Difficulty: MediumSource: NCERT equation (1.29)Topic: oxidation-and-reduction

In CuO + H₂ → Cu + H₂O, which statement is correct?

1CuO is oxidised and H₂ is reduced.2Both CuO and H₂ are oxidised.3H₂ is oxidised and CuO is reduced.4Neither reactant changes.

Question 16

Corrosion near the sea

Difficulty: HardSource: Platform application - NCERT Section 1.3.1 CorrosionTopic: oxidation-and-reduction

An unpainted iron gate near the sea develops a reddish-brown coating faster than a similar gate in a dry area. Which explanation and prevention pair is correct?

1Salt converts iron directly into paint; washing with more salt prevents it.2Only sunlight causes the coating; keeping the gate wet prevents it.3Nitrogen in air forms rust; scratching the surface prevents it.4Moisture and oxygen promote corrosion; painting the gate creates a protective barrier.

Question 17

Decomposition numbering

Difficulty: HardSource: NCERT equations (1.20)-(1.23)Topic: combination-and-decomposition-reactions

Which statement about the NCERT equation sequence is correct?

1(1.20) is calcium carbonate decomposition and (1.21) is lead nitrate decomposition.2(1.20) is electrolysis of water and (1.21) is silver chloride decomposition.3The electrolysis equation is numbered (1.21).4Silver bromide decomposition is numbered (1.22).

Question 18

Two-reaction classification

Difficulty: HardSource: NCERT Sections 1.2.3-1.2.4Topic: displacement-and-double-displacement-reactions

How should these reactions be classified in order? Zn + CuSO₄ → ZnSO₄ + Cu; Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

1combination, decomposition2displacement, double displacement3double displacement, displacement4oxidation only, combination

Question 19

Complete oxidation answer

Difficulty: HardSource: NCERT Exercise 16Topic: oxidation-and-reduction

Which pair correctly gives two examples of oxidation by gain of oxygen?

1CuO → Cu and PbO → Pb2AgCl → Ag and CaCO₃ → CaO32Mg + O₂ → 2MgO and 2Cu + O₂ → 2CuO4H₂O → H₂ and FeSO₄ → Fe₂O₃

Question 20

Rancidity reasoning

Difficulty: HardSource: NCERT Section 1.3.2 and Exercise 19Topic: ncert-exercises-and-revision

Why are oily food packets flushed with nitrogen?

1Nitrogen changes oil into water.2Nitrogen increases the packet temperature.3Nitrogen makes oxidation faster.4Nitrogen limits contact with oxygen and delays rancidity.

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Chemical Reactions and Equations quiz

Select your answers

Evidence of reaction

Figure 1.2

Skeletal equation

Conservation of mass

Steam symbol

Combination pattern

Balancing sodium and water

Reaction condition

Whitewashing

Ferrous sulphate

Electrolysis volumes

Photography reaction

Displacement observation

Precipitation

Redox identification

Corrosion near the sea

Decomposition numbering

Two-reaction classification

Complete oxidation answer

Rancidity reasoning

Preparing your questions...

Tell us what to fix next

Select your answers

Evidence of reaction

Figure 1.2

Skeletal equation

Conservation of mass

Steam symbol

Combination pattern

Balancing sodium and water

Reaction condition

Whitewashing

Ferrous sulphate

Electrolysis volumes

Photography reaction

Displacement observation

Precipitation

Redox identification

Corrosion near the sea

Decomposition numbering

Two-reaction classification

Complete oxidation answer

Rancidity reasoning