Match the Column I with Column II. Processes Products (i) Combination (a) Na + Cl 2 (ii) Thermal decomposition (b) NaCl + H 2 O (iii) Electrolysis (c) Ca ( OH ) 2 (iv) Precipitation (d) CaO + CO 2 (v) Neutralisation (e) BaSO 4 + NaCl

CaO + H 2 O → Ca ( OH ) 2 This reaction is a combination reaction as calcium oxide and water combines to form a single product that is calcium hydroxide. CaCO 3 → ∆ CaO + CO 2 When any compound is decomposed by the action of heat then the reaction is known as thermal decomposition reaction. In the above reaction calcium carbonate decomposed into calcium oxide and carbon dioxide. On electrolysis of aqueous sodium chloride hydrogen ions from the water are discharged at the negative electrode as hydrogen gas and chloride ions from the dissolved sodium chloride are discharged at the positive electrode as chlorine gas. Barium sulphate which forms as a crystalline precipitate, when barium chloride reacts with sodium sulphate. This reaction involves an acid ( HCl ) reacting with a base ( NaOH ), producing a salt ( NaCl ) and water. Therefore, it is a neutralization reaction. Column i Column ii (i) Combination (c) Ca ( OH ) 2 (ii) Thermal decomposition (d) CaO + CO 2 (iii) Electrolysis (a) Na + Cl 2 (iv) Precipitation (e) BaSO 4 + NaCl (v) Neutralisation (b) NaCl + H 2 O

Observe the two test tubes A and B in the diagram given below and answer the following questions. In which test tube reaction will take place. Name the type of reaction.

1. In test tube A iron nail is immersed in copper sulphate solution and iron is more reactive than copper due to which reaction will take place in test tube A and iron sulphate will be formed as product. In test tube B no reaction will occur. 2. The reaction in which more reactive element displaces less reactive element from its solution is known as displacement reaction.

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All In One ICSE Chemistry>Chapter 2 - Chemical Changes and Reactions>EXAM PRACTICE>Q 15

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Name the precipitate formed when barium chloride solution is mixed with sodium sulphate solution.

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Important Questions on Chemical Changes and Reactions

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All In One ICSE Chemistry>Chapter 2 - Chemical Changes and Reactions>EXAM PRACTICE>Q 16

The products formed by neutralisation reaction are

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All In One ICSE Chemistry>Chapter 2 - Chemical Changes and Reactions>EXAM PRACTICE>Q 17

Electrolysis of acidulated water is a decomposition reaction. The molar ratio of hydrogen and oxygen gas liberated during electrolysis of water is

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All In One ICSE Chemistry>Chapter 2 - Chemical Changes and Reactions>EXAM PRACTICE>Q 18

Match the Column I with Column II.

Processes	Products
(i) Combination	(a) $Na + {Cl}_{2}$
(ii) Thermal decomposition	(b) $NaCl + H_{2} O$
(iii) Electrolysis	(c) $Ca (OH)_{2}$
(iv) Precipitation	(d) $CaO + {CO}_{2}$
(v) Neutralisation	(e) ${BaSO}_{4} + NaCl$