{"id":28870,"date":"2018-07-13T08:45:53","date_gmt":"2018-07-13T08:45:53","guid":{"rendered":"https:\/\/cbselibrary.com\/?p=28870"},"modified":"2022-03-28T18:59:15","modified_gmt":"2022-03-28T13:29:15","slug":"new-simplified-chemistry-class-9-icse-solutions-chemical-changes-and-reactions","status":"publish","type":"post","link":"https:\/\/cbselibrary.com\/new-simplified-chemistry-class-9-icse-solutions-chemical-changes-and-reactions\/","title":{"rendered":"New Simplified Chemistry Class 9 ICSE Solutions Chemical Changes and Reactions"},"content":{"rendered":"

New Simplified Chemistry Class 9 ICSE Solutions Chemical Changes and Reactions<\/h2>\n

ICSE Solutions<\/a>Selina ICSE Solutions<\/a>ML Aggarwal Solutions<\/a><\/p>\n

Viraf J Dalal Chemistry Class 9 Solutions and Answers<\/strong><\/p>\n

Simplified Chemistry<\/a>Physics<\/a>Chemistry<\/a>Biology<\/a>Maths<\/a>Geography<\/a>HistoryCivics<\/a><\/p>\n

Exercise<\/strong><\/span><\/p>\n

Question 1.(1986)<\/strong><\/span>
\nExplain : <\/strong>Silver nitrate solution is kept in coloured reagent bottles in the laboratory.
\nAnswer:
\n<\/strong><\/span>\"New
\nSilver nitrate gets decomposed by sunlight. Hence silver nitrate is stored in coloured reagent bottles.<\/p>\n

Question 1.(1987)<\/strong><\/span>
\nGive an example of an endothermic reaction.
\nAnswer:
\n\"New
\n<\/strong><\/span><\/p>\n

Question 1.(1988)<\/strong><\/span>
\nState in each case if the reaction represents oxidation or reduction
\n\"New
\nAnswer:
\n\"New
\n\"New
\n<\/strong><\/span><\/p>\n

Question 1.(1989)<\/strong><\/span>
\nReactions can be classified as : Direct combination, decomposition, simple displacement, double decomposition, Redox reactions. State which of the following types, takes place in the reactions given below<\/p>\n

    \n
  1. Cl2<\/sub> + 2KI \u2192 2KCl + l2<\/sub><\/li>\n
  2. 2Mg + O2<\/sub> \u2192 2MgO<\/li>\n
  3. SO2<\/sub> + 2H2<\/sub>O + Cl2<\/sub> \u2192 2HCl + H2<\/sub>SO4<\/sub><\/li>\n
  4. AgNO3<\/sub> + HCl \u2192 AgCl + HNO3<\/sub><\/li>\n
  5. 4HNO3<\/sub> \u2192 4NO2<\/sub> + 2H2<\/sub>O + O2<\/sub><\/li>\n<\/ol>\n

    Answer:<\/strong><\/span><\/p>\n

      \n
    1. Cl2<\/sub> + 2KI \u2192 2KCl + I2<\/sub> \u2014 Simple displacement<\/li>\n
    2. 2Mg + O2<\/sub> \u2192 2MgO \u2014 Direct combination<\/li>\n
    3. SO2<\/sub> + 2H2<\/sub>O + Cl2<\/sub> \u2192 2HCl + H2<\/sub>SO4<\/sub> \u2014 Redox reaction<\/li>\n
    4. AgNO3<\/sub> + HCl \u2192 AgCl + HNO3<\/sub> \u2014 Double decomposition<\/li>\n
    5. 4HNO3<\/sub> \u2192 4NO2<\/sub> + 2H2<\/sub>O + O2<\/sub> \u2014 Decomposition reaction<\/li>\n<\/ol>\n

      Question 1.(1990)<\/strong><\/span>
      \nGive one reason why magnetizing a piece of steel is a physical change.
      \nAnswer:<\/strong><\/span>
      \nThere is no change in composition.<\/p>\n

      Question 1.(1993)<\/strong><\/span>
      \nState whether the following are oxidation or reduction
      \n\"New
      \nAnswer:
      \n\"New
      \n<\/strong><\/span><\/p>\n

      Additional Questions<\/strong><\/span><\/p>\n

      Question 1.<\/strong><\/span>
      \nExplain the term chemical reaction with special reference to reactants and products.
      \nAnswer:<\/strong><\/span>
      \nChemical change :<\/strong> \u201cIs reprsentation of a chemical change in substances taking part and are called reactants written on left side of \u2192
      \n\"New
      \nWhen Zn react with dil HCl, new substance ZnCl and H2<\/sub> are produced as a result of chemical change reactants are seperated by + sign and products formed are also separated by + sign.<\/p>\n

      Question 2.<\/strong><\/span>
      \nGive a suitable example with equation to show the representation of a chemical reaction.
      \nAnswer:<\/strong><\/span>
      \nIron and sulphuric acid dilute which react to produce ferrous sulphate and hydrogen gas can be represented by a chemical equation.
      \nIron + dil. sulphuric acid \u2192 ferruous sulphate and hydrogen
      \n\"New<\/p>\n

      Question 3.<\/strong><\/span>
      \nA chemical reaction is often accompanied by external indications or characteristics.
      \nGive two examples where a chemical reaction is accompanied by a change in colour of the reactants & products on completion of the reaction.
      \nAnswer:<\/strong><\/span>
      \nA chemical reaction is accompanied by change in colour of reactants and products<\/p>\n

      \"New<\/p>\n

      Question 4.<\/strong><\/span>
      \nGive balanced equations for reactions involving evolution of a gas on addition of dilute acid to<\/p>\n

      (a)<\/strong> sodium sulphite
      \n(b)<\/strong> calcium carbonate.<\/p>\n

      Answer:
      \n\"New
      \n<\/strong><\/span><\/p>\n

      Question 5.<\/strong><\/span>
      \nGive a balanced equation for conversion of<\/p>\n

      (a)<\/strong> an ammonium salt to a basic gas
      \n(b)<\/strong> a soluble lead salt to an insoluble lead salt \u2013 formed as a white precipitate.<\/p>\n

      Answer:
      \n<\/strong><\/span>(a)<\/strong> Ammonium salt [NH4<\/sub>Cl] on heating produces NH3<\/sub>(g) which is a basic gas
      \n\"New
      \n(b)<\/strong> Lead nitrate when reacts with sodium chloride insoluble white ppt. of lead chloride is formed
      \n\"New<\/p>\n

      Question 6.<\/strong><\/span>
      \nChemical reactions may proceed with evolution or absorption of heat. Give an example of each.
      \nAnswer:<\/strong><\/span>
      \nChemical reaction is characterised by evolution of heat :
      \n<\/strong>\"New
      \nChemical reaction is characterised by absorption of heat :
      \n\"New
      \n<\/strong><\/p>\n

      Question 7.<\/strong><\/span>
      \nDefine the following types of chemical changes or reactions with a suitable example each.<\/p>\n

      (a)<\/strong> Direct combination reaction or synthesis
      \n(b)<\/strong> Decomposition reaction
      \n(c)<\/strong> Displacement reaction or substitution reaction
      \n(d)<\/strong> Double decomposition reaction<\/p>\n

      Answer:<\/strong><\/span>
      \n(a) Direct Combination Reaction Of Synthesis :<\/strong>
      \n\u201cThose reactions in which two or more substances [element or elements and compound or compounds] combine and form a new substance\u201d
      \nH2<\/sub> + O2<\/sub> \u2192 H2<\/sub>O Hydrogen combines with oxygen to produce a new substance water.
      \n(b) Decomposition Reaction :<\/strong>
      \n\u201cThose reactions in which a compound splits up into two or more simpler substances\u201d
      \n\"New
      \n(c) Displacement Reaction Or Substitution Reaction :<\/strong>
      \n\u201cThose reactions in which one element takes place of another element in a compound, are known as substitution reactions.\u201d
      \n\"New
      \n(d) Double-De-Composition Reaction :<\/strong>
      \n\u201cThose reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions.\u201d
      \n\"New<\/p>\n

      Question 8.<\/strong><\/span>
      \nGive a balanced equation for a direct combination reaction involving :<\/p>\n

      (a)<\/strong> Two elements \u2014 one of which is a neutral gas and the other a yellow non\u00acmetal
      \n(b)<\/strong> Two elements \u2013 one of which is a neutral gas and the other a monovalent metal
      \n(c)<\/strong> Two compounds \u2013 resulting in formation of a weak acid<\/p>\n

      Answer:<\/strong><\/span>
      \n(a)<\/strong> Direct Combination of two elements one of which is a neutral gas and the other a yellow non-metal
      \n\"New
      \n(b)<\/strong> Direct Combination of two elements one of which is a neutral and the other a monovalent metal
      \n\"New
      \n(c)<\/strong> Direct Combination of two compounds to form weak acid.
      \n\"New<\/p>\n

      Question 9.<\/strong><\/span>
      \nGive balanced equations for the following reactions of synthesis involving formation of :<\/p>\n

      (a)<\/strong> An acid \u2013 from sulphur dioxide gas
      \n(b)<\/strong> An alkali \u2013 from a basic oxide \u2013 sodium oxide
      \n(c)<\/strong> A salt \u2013 from a trivalent metal and a coloured gas.<\/p>\n

      Answer:<\/strong><\/span><\/p>\n

      \"New<\/p>\n

      Question 10.<\/strong><\/span>
      \nConvert \u2014 (a)<\/strong> nitrogen to ammonia (b)<\/strong> hydrogen to hydrogen chloride \u2013 by a direct combination reaction.
      \nAnswer:<\/strong><\/span>
      \nBy direct combination reaction :
      \n<\/strong>(a)<\/strong> Nitrogen to ammonia<\/p>\n

      \"New
      \n(b)<\/strong> Hydrogen to hydrogen chloride<\/p>\n

      \"New<\/p>\n

      Question 11.<\/strong><\/span>
      \nGive balanced equations for thermal decomposition of :<\/p>\n

      (a)<\/strong> lead carbonate
      \n(b)<\/strong> lead nitrate
      \n(c)<\/strong> ammonium dichromate
      \n(d)<\/strong> mercury [II] oxide
      \n(e)<\/strong> calcium hydroxide<\/p>\n

      Answer:<\/strong><\/span>
      \nDecomposition of :
      \n\"New
      \n<\/strong><\/p>\n

      Question 12.<\/strong><\/span>
      \nDefine \u2013 a thermal dissociation reaction with a suitable example. Give an example of a photochemical decomposition reaction. Name a metallic oxide which on thermal decomposition is reduced to a metal.
      \nAnswer:<\/strong><\/span>
      \nThermal Dissociation :<\/strong>
      \n\u201cA decomposition reaction \u2014 in which a substance dissociates \u2014 into two or more simpler substances on application of heat.\u201d
      \n\"New<\/p>\n

      Question 13.<\/strong><\/span>
      \nDefine a displacement reaction with a suitable example. State how it is represented. Give a reason why zinc displaces hydrogen from dilute sulphuric acid but copper docs not.
      \nAnswer:<\/strong><\/span>
      \nDisplacement reaction :<\/strong> \u201cIs a chemical reaction in which an element [or radical] replaces another element in a compound.\u201d
      \n\"New
      \nZinc (more electropositive) and being above [H] in activity series displaces hydrogen from dilute sulphuric acid but copper is below [H] in electrochemical series cannot displace hydrogen from sulphuric acid.<\/p>\n

      Question 14.<\/strong><\/span>
      \nExplain the term double decomposition \u2014 precipitation reaction. Give a balanced equation for the preparation of two different insoluble lead salts from their salt solutions by \u2014 double decomposition \u2014 precipitation.
      \nAnswer:<\/strong><\/span>
      \nDouble decomposition reaction is precipitation reaction.
      \ni. e. in which ppt. is formed
      \n\u201cReaction between two compounds in aqueous state, to give two new compounds one of which is precipitate (or insoluble).\u201d
      \n\"New<\/p>\n

      Question 15.<\/strong><\/span>
      \nExplain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
      \nAnswer:<\/strong><\/span>
      \nPrecipitation reactions are used to identify the positive ions from their colours.
      \n\"New<\/p>\n

      Question 16.<\/strong><\/span>
      \nDefine the term \u2013 double decomposition \u2013 neutralization reaction with a suitable representation.
      \nConvert :<\/strong>
      \n(a)<\/strong> an insoluble base
      \n(b)<\/strong> a soluble base to their respective soluble salts by neutralization reaction.
      \nAnswer:<\/strong><\/span>
      \nWhen acid reacts with a base salt and water are formed and this is called Neutralisation.
      \nDouble-decomposition \u2014 Neutralisation reaction :
      \n\u201cIs the chemical reaction between two compounds (acid and base) to interchange radicals and produce salt and water.\u201d
      \nThis is represented as :
      \n\"New
      \n<\/strong><\/p>\n

      Question 17.<\/strong><\/span>
      \nExplain the term energy changes in a chemical change or reaction. Give an example with a balanced equation, for each of the following reactions:<\/p>\n

      (a)<\/strong> exothermic reaction
      \n(b)<\/strong> endothermic reaction
      \n(c)<\/strong> photochemical reaction
      \n(d)<\/strong> electrochemical reaction.<\/p>\n

      Answer:<\/strong><\/span>
      \nEnergy Changes In A Chemical Reaction :<\/strong>
      \n\u201cIs the difference between the chemical energy of the REACTANTS and the PRODUCTS\u201d.
      \nExample of :
      \n\"New
      \n\"New
      \n<\/strong><\/p>\n

      Question 18.<\/strong><\/span>
      \nSupply of energy maybe required to initiate a reaction. State the different forms with a suitable example of reactions initiated by supply of energy.
      \nAnswer:<\/strong><\/span>
      \nTo Start A Reaction Energy Needed In The Form :
      \n\"New
      \n<\/strong><\/p>\n

      Chemical Changes & Reactions \u2013 Unit Test Paper 2<\/span><\/strong><\/p>\n

      Q.1. Complete the statements by filling in the blank with the correct word\/s :<\/strong><\/p>\n

      Question 1.<\/strong><\/span>
      \nDirect combination reaction of sulphur dioxide with water gives [H2<\/sub>SO4<\/sub>\/H2<\/sub>SO3<\/sub>\/H2<\/sub>S2<\/sub>O7<\/sub>].
      \nAnswer:<\/strong><\/span>
      \nDirect combination reaction of sulphur dioxide with water gives H2<\/sub>SO3<\/sub>.<\/strong><\/p>\n

      Question 2.<\/strong><\/span>
      \nFormation of hydrogen chloride from hydrogen and chlorine is an example of [photochemical reaction\/electrochemical reaction].
      \nAnswer:<\/strong><\/span>
      \nFormation of hydrogen chloride from hydrogen and chlorine is an example of photochemical reaction.<\/strong><\/p>\n

      Question 3.<\/strong><\/span>
      \nThe reaction of hydrogen burning in oxygen to give a neutral liquid is an example of [exothermic\/ endothermic] reaction.
      \nAnswer:<\/strong><\/span>
      \nThe reaction of hydrogen burning in oxygen to give a neutral liquid is an example of exothermic<\/strong> reaction.<\/p>\n

      Question 4.<\/strong><\/span>
      \nThe neutral gas evolved when lead nitrate undergoes thermal decomposition is [nitrogen dioxide\/oxygen\/nitrogen].
      \nAnswer:<\/strong><\/span>
      \nThe neutral gas evolved when lead nitrate undergoes thermal decomposition is nitrogen dioxide.<\/strong><\/p>\n

      Question 5.<\/strong><\/span>
      \nThe reddish brown precipitate obtained during a double decomposition precipitation reaction between an iron salt and an alkali is [iron [III] hydroxide\/iron [III] hydroxide]
      \nAnswer:<\/strong><\/span>
      \nThe reddish brown precipitate obtained during a double decomposition \u2013 precipitation reaction between an iron salt and an alkali is iron [III] hydroxide.<\/strong><\/p>\n

      Q.2. Select the correct answer from A, B, C, D and E for each statement given below :<\/strong>
      \nA :<\/strong> Ammonia
      \nB :<\/strong> Hydrogen chloride
      \nC :<\/strong> Hydrogen
      \nD :<\/strong> Nitrogen dioxide
      \nE :<\/strong> Nitric oxide
      \nState the gaseous product formed, when<\/p>\n

      Question 1.<\/strong><\/span>
      \nAn active metal reacts with dilute sulphuric acid.
      \nAnswer:<\/strong><\/span>
      \nC : Hydrogen<\/p>\n

      Question 2.<\/strong><\/span>
      \nA metallic nitrate undergoes thermal decomposition giving a coloured gas.
      \nAnswer:<\/strong><\/span>
      \nD : Nitrogen dioxide<\/p>\n

      Question 3.<\/strong><\/span>
      \nTwo gases one of them neutral, combines by absorption of light energy.
      \nAnswer:<\/strong><\/span>
      \nB : Hydrogen chloride<\/p>\n

      Question 4.<\/strong><\/span>
      \nAn ammonium salt reacts with an alkali.
      \nAnswer:<\/strong><\/span>
      \nA: Ammonia<\/p>\n

      Question 5.<\/strong><\/span>
      \nAn exothermic reaction takes place between ammonia and a neutral gas.
      \nAnswer:<\/strong><\/span>
      \nE : Nitric oxide<\/p>\n

      Q.3. Give a balanced equation for each of the following types of reactions :<\/strong><\/p>\n

      Question 1.<\/strong><\/span>
      \nA direct combination reaction between phosphorus and a neutral gas.
      \nAnswer:<\/strong><\/span>
      \nPhosphorus with neutral gas (O2<\/sub>)
      \n\"New<\/p>\n

      Question 2.<\/strong><\/span>
      \nA soluble salt of lead formed from an insoluble base by double decomposition \u2013 neutralisation.
      \nAnswer:<\/strong><\/span>
      \nSoluble salt of lead formed from insoluble base by double-decomposition by neutralization.
      \n\"New<\/p>\n

      Question 3.<\/strong><\/span>
      \nA thermal decomposition reaction of a salt \u2013 which results in the formation of nitrogen gas.
      \nAnswer:<\/strong><\/span>
      \nThermal decomposition of a salt with the formation of nitrogen gas.
      \n\"New<\/p>\n

      Question 4.<\/strong><\/span>
      \nA synthesis reaction between a metal & a non-metal resulting in formation of an insoluble salt of iron.
      \nAnswer:<\/strong><\/span>
      \nSynthesis reaction between a metal and non-metal to form insoluble salt of iron [FeS]
      \n\"New<\/p>\n

      Question 5.<\/strong><\/span>
      \nA decomposition reaction of a salt which leaves behind a silvery metal.
      \nAnswer:<\/strong><\/span>
      \nDecomposition reaction of a salt leaving behind a silvery metal.
      \n\"New<\/p>\n

      Q.4. Differentiate between the following :<\/strong><\/p>\n

      Question 1.<\/strong><\/span>
      \nSynthesis reaction & a substitution reaction.
      \nAnswer:<\/strong><\/span>
      \nSynthesis and substitution reaction :<\/strong><\/p>\n