ICSE BOARD PAPER - 2007 - X - Chemistry 2007 Set 1

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  • Q1

    (a) From the list given below, select the word(s) required to correctly complete blanks (i) to (v) in the following passage:

    Ammonia, ammonium, carbonate, carbon dioxide, hydrogen, hydronium, hydroxide, precipitate, salt, water.

    A solution X turns blue litmus red, so it must contain (i) _______ ions; another solution Y turns red litmus blue and therefore, must contain (ii)_______ions. When solutions X and Y are mixed together, the products will be a (iii)________ and (iv) _______. If a piece of magnesium is put into solution X, (v) ________gas would be evolved.                 [5]

    (Note: Words chosen from the list are to be used only once. Write the answers as (a) (i),(ii),(iii) and so on. Do not copy the passage.)

     

    (b) From the list of characteristics given below, select five characteristics which are relevant to non-metals and their compounds:

    A. Ductile

    B. Conduct electricity

    C. Brittle

    D. Acidic oxides

    E.Basic oxides

    F.Discharged at anode

    G.Discharged at cathode

    H.Ionic chlorides

    I.Covalent chlorides

    J.Reaction with dilute sulphuric acid yields hydrogen

    K.1, 2 or 3 valence electrons

    L. 5, 6 or 7 valence electrons

    (Write the five letters corresponding to the correct characteristics)     [5]

     

    (c) A group of elements in the Periodic Table are given below (Boron is the first member of the group and Thallium is the last.)

    Boron

    Aluminium

    Gallium

    Indium

    Thallium

    Answer the following questions in relation to the above group of elements:

    (i) Which element has the most metallic character?

    (ii) Which element would be expected to have the highest electronegativity?

    (iii) If the electronic configuration of aluminium is 2, 8, 3, how many electrons are there in the outer shell of Thallium?

    (iv) The atomic number of Boron is 5. Write the chemical formula of the compound formed when Boron reacts with Chlorine.

    (v) Will the elements in the group to the right of this Boron group be more metallic or less metallic in character? Justify your answer.              [5]

     

    (d) Match the following:

       Column A                        Column B

    1. Acid salt                 Sodium potassium carbonate

    2. Mixed salt               Alum

    3. Complex salt           Sodium carbonate

    4. Double salt             Sodium zincate

    5. Normal salt             Sodium hydrogen carbonate [5]

     

    (e) Give the IUPAC names of the following compounds numbered (i) to (v). The IUPAC names of the compounds on the left are to guide you into giving the correct IUPAC names of the compounds on the right.      [5]

     

     

     

     

    (f) A sample of ammonium nitrate when heated yields 8.96 liters of steam (measured at STP).

          

    (i) What volume of dinitrogen oxide is produced at the same time as 8.96 litres of steam?

    (ii) What mass of ammonium nitrate should be heated to produce 8.96 litres of steam?

    (iii) Determine the percentage of oxygen in ammonium nitrate (O = 16).      [5]

     

    (g) Write balanced equations for the following reactions:

    (i) Lead sulphate from lead nitrate solution and dilute sulphuric acid.

    (ii) Copper sulphate from copper and concentrated sulphuric acid.

    (iii)Lead chloride from lead nitrate solution and sodium chloride solution.

    (iv)Ammonium sulphate from ammonia and dilute sulphuric acid.

    (v) Sodium chloride from sodium carbonates solution and dilute hydrochloric acid.                [5]

     

    (h) Choose A, B, C or D to match the descriptions (i) to (v) below. Some alphabets may be repeated.

    (A)  Non-electrolyte

    (B)  Strong electrolyte

    (C)   Weak electrolyte

    (D)   Metallic conducto

    (i)  Molten ionic compound

    (ii) Caron tetrachloride

    (iii) An aluminium wire

    (iv) A solution containing solvent molecules, solute molecules and ions formed by the dissociation of solute molecules.

    (v) A sugar solution with sugar molecules and water molecules. [5]

    Marks:40
    Answer:

    (a) A solution X turns blue litmus red, so it must contain (i) hydronium ion; another solution Y turns red litmus blue and therefore, must contain (ii) hydroxide ions. When solutions X and Y are mixed together, the products will be (iii) salt and (iv) water. If a piece of magnesium is put into solution X, (v) hydrogen gas would be evolved.

     

    (b)

    C  Brittle

    D  Acidic oxides

    F  Discharged at anode

    I  Covalent Chlorides

    L  5, 6 or 7 valence electrons

     

    (c)

    (i)  Thallium                       

    (ii)  Boron

    (iii) 3 electrons           

    (iv) BCl3

    (v)Elements in the group to the right of this Boron group will be less metallic in character. This is so because on moving across a period, nuclear pull increases due to the increase in atomic number and thus, atomic decreases.  Hence. elements cannot lose electrons easily. Therefore, the metallic nature decreases across a period, moving from left to right.

     

    (d)    Column A                   Column B

            1. Acid salt                 Sodium hydrogen carbonate

            2. Mixed salt               Sodium potassium carbonate

            3. Complex salt           Sodium zincate

            4. Double salt             Alum

            5. Normal salt             Sodium carbonate

     

    (e)

    (i)  Propyne  

    (ii) Pentan-3-ol

    (iii) 2-methylpropane

    (iv) Ethanoic acid                  

    (iv) 1,2 dichloroethane 


     

    (h)

    (i) Molten ionic compound: B. strong electrolyte

    (ii) Carbon tetrachloride: A. non-electrolyte

    (iii) An aluminium wire: D. metallic conductor

    (iv) A solution containing solvent molecules, solute molecules and ions formed by the dissociation of solute molecules: C. weak electrolyte

    (v) A sugar solution with sugar molecules and water molecules: A non-electrolyte

    View Answer
  • Q2

    (a) Some properties of sulphuric acid are listed below. Choose the property A, B, C or D; which is responsible for the reaction (i) to (v). Some properties may be repeated:  [5]

    A  Acid

    B  Dehydrating agent

    C  Non-volatile acid

    D  Oxidising agent


    (b)   

    (i)Name the acid formed when sulphur dioxide dissolves in water.

    (ii)Name the gas released when sodium carbonate is added to a solution of sulphur dioxide.

    (iii) What are the two necessary conditions for the direct combination of sulphur dioxide and chlorine forming sulphuryl chloride?

    (iv)State the property of sulphur dioxide which causes potassium permanganate to change from purple colour to colourless. [5] 

    Marks:10
    Answer:

     



     

    Thus, when sulphur dioxide is dissolved in water, sulphurous acid is formed.


    Carbon dioxide is released when sodium carbonate is added to a solution of sulphur dioxide.

    (iii)Two necessary conditions for the direct combination of sulphur dioxide and chlorine to form sulphuryl chloride are:

    1. Sulphur dioxide and chlorine should be dry.

    2. The reaction takes place in the presence of sunlight.

    (iv) Moist sulphur dioxide is a powerful reducing agent. In the presence of oxidizing agents, it easily takes up an atom of oxygen.

     

    Purple potassium permanganate is reduced to colourless manganese sulphate.

     


     

     

    View Answer
  • Q3

    (a)   

    (i) Of the two gases, ammonia and hydrogen chloride, which one is more dense? Name the method of collection of this gas.

    (ii) Give one example of a reaction between the above two gases, which produces a solid compound. [3]

     

    (b) Write a balanced equation for a reaction in which ammonia is oxidised by:

    (i) A metal oxide;  

    (ii) A gas which is not oxygen. [2]

     

    (c) The figure given below illustrates the apparatus used in the laboratory preparation of nitric acid.  [5]

     

    (i) Name A (a liquid), B (a solid) and C (a liquid).

          (Do not give the formulae)

    (ii) Write an equation to show how nitric acid undergoes decomposition.

    (iii) Write the equation for the reaction in which copper is oxidised by concentrated nitric acid.

    Marks:10
    Answer:

    (a)

    (i) Hydrogen chloride is denser. Since hydrogen chloride is heavier than air, it is collected by upward displacement of air.

    (b)   

    (i) A reaction in which ammonia is oxidised by a metal oxide:

          

    (ii) A reaction in which ammonia is oxidised by a gas which is not oxygen:

           

    (c)   

    (i)  A: Concentrated sulphuric acid

         B: Potassium nitrate

         C: Nitric acid

     

    View Answer
  • Q4

    (a) The following is an extract from ‘Metals in the Service of Man, Alexander and Street/Pelican 1976’:

    ‘Alumina (aluminum oxide) has a very high melting point of over 2000C so that it cannot readily be liquefied. However, conversion of alumina to aluminium and oxygen, by electrolysis, can occur when it is dissolved in some other substance.’

     

    (i)Which solution is used to react with bauxite as a first step in obtaining pure aluminium oxide?

    (ii)The aluminum oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide. Write the equation for this reaction.

    (iii) Name the element which serves both as the anode and the cathode in the extraction of aluminium.

    (iv) Write the equation for the reaction that occurs at the cathode during the extraction of aluminium by electrolysis.

    (v)Give the equation for the reaction which occurs at the anode when aluminium in purified by electrolysis.  [5]

     

     

    (b)   

    (i) Name the charged particles which attract one another to form electrovalent compounds.

    (ii) In the formation of electrovalent compounds, electrons are transferred from one element to another. How are electrons involved in the formation of a covalent compound?

    (iii) The electronic configuration of nitrogen is 2, 5. How many electrons in the outer shell of a nitrogen atom are not involved in the formation of a nitrogen molecule?

    (iv) In the formation of magnesium chloride by direct combination between magnesium and chlorine), name the substance that is oxidised and the substance that is reduced.   [5]

    Marks:10
    Answer:

     

    (a)(i) Concentrated caustic soda solution is used to react with bauxite as a first step in obtaining pure aluminium oxide.


    (iii) Carbon serves both as the anode and the cathode in the extraction of aluminium.
    Anode: Thick rods of graphite are suspended into the fused electrolyte.
    Cathode: Inner carbon lining of the electrolytic cell serves as the cathode.



    Anode is oxidised to carbon monoxide, which further forms carbon dioxide.

     


    (b)   

    (i) Ions are the charged particles which attract one another to form electrovalent compounds.

    (ii) A covalent bond is formed by the mutual sharing of electron pairs between two atoms.

    (iii) 2 electrons in the outer shell of a nitrogen atom are not involved in the formation of a nitrogen molecule.

    (iv) In the formation of magnesium chloride (by direct combination between magnesium and chlorine), magnesium is oxidised and chlorine is reduced.

         

     

          

    View Answer
  • Q5

    Copy and complete the following table which relates to three homologous series of Hydrocarbons:            [10]

     

    General Formula

    CnH2n

    CnH2n-2

    CnH2n+2

    IUPAC name of the homologous series

     

     

     

    Characteristic bond type

     

     

    Single bonds

    IUPAC name of the First member of the series

     

     

     

    Type of reaction with chlorine

     

    Addition

     

     

     

    Marks:10
    Answer:

    General Formula

    CnH2n

    CnH2n-2

    CnH2n+2

    IUPAC name of the homologous series

    Alkenes

    Alkynes

    Alkanes

    Characteristic bond type

    Double bonds

    Triple bonds

    Single bonds

    IUPAC name of the First member of the series

    Ethene

    Ethyne

    Methane

    Type of reaction with chlorine

    Addition

    Addition

    Substitution

     

    View Answer
  • Q6

    (a) 

    (i) HCl, HNO3 and H2SO4 are the formulae of three compounds. Which of these compounds has the highest boiling point and which has the lowest?

    (ii) Dilute hydrochloric acid and dilute sulphuric acid, both are colourless solutions. How will the addition of barium chloride solution to each help to distinguish between the two?

    (iii) You enter a laboratory after a class and have to complete the Fountain Experiment. 

    How will you be able to tell whether the gas used in the experiment was hydrogen chloride or ammonia?  [5]

     

    (b)Write balanced equations for the reaction of dilute hydrochloric acid with each of the following:

    (i) Iron                           

    (ii) Sodium hydrogen carbonate

    (iii) Iron (II) sulphide  

    (iv) Sodium sulphite

    (v) Sdoium thiosulphate solution.  [5]

    Marks:10
    Answer:

    (a)

    (i)  H2SO4has the highest boiling point and HCl has the lowest boiling point.

    (ii) Dilute sulphuric acid, if added to a solution of barium chloride, forms a white precipitate of barium sulphate.

           

    Barium sulphate does not dissolve in hydrochloric acid.

     

    (iii) If hydrogen chloride was used in the experiment, a red fountain would be visible in the round bottom flask because hydrogen chloride gas, being acidic in nature, turns blue litmus solution red.

    If ammonia was used in the experiment, a blue fountain would be visible in the round bottomed flask because ammonia gas, being basic in nature, turns red litmus solution blue.

     

    View Answer
  • Q7

    (a)A compound X consists of 4.8% carbon and 95.2% bromine by mass.

    (i)Determine the empirical formula of this compound working correct to one decimal place (C=12; Br =80).

    (ii)If the vapour density of the compound is 252, what is the molecular formula of the compound?

    (iii)Name the type of chemical reaction by which X can be prepared from ethane.  [5]

     

    (b)Salts A,B,C,D and E undergo reaction (i) to (v) respectively. Identify the anion present in these salts on the basis of these reactions. Tabulate your answers in the format given below:

    (i) When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric acid, is formed.

    (ii) Addition of dilute hydrochloric acid to B produces a gas which turns lead acetate paper black.

    (iii) When a freshly prepared solution of ferrous sulphate is added to a solution of C and concentrated sulphuric acid is gently poured from the side of the test-tube, a brown ring is formed.

    (iv) When dilute sulphuric acid is added to D, a gas is produced which turns acidified potassium dichromate solution from orange to green.

    (v) Addition of dilute hydrochloric acid to E produces effervescence. The gas produced turns lime water milky but does not affect acidified potassium dichromate solution.        [5]

     

    Salt

    Anion

    A

     

    B

     

    C

     

    D

     

    E

     

     

     

    Marks:10
    Answer:

    (a)

    (i)   Carbon : 4.8%, Bromine : 95.2%

    Element

    Percentage Mass

    Atomic Mass

    Number of atoms

    Simplest Ratio

    Carbon (C)

    4.8

    12

    4.8/12 = 0.4

    0.4/0.4=1

    Bromine(Br)

    95.2

    80

    95.2/80=1.2

    1.2/0.4=3

      Thus, the ratio of C : Br atoms =1:3

    The empirical formula of the compound is CBr3

     

    (ii)    Mol. wt =2 x Vapour Density

                         =2 x 252

                         = 504

    or n = Molecular weight / Empirical formula weight

           = 504/12 + (3 x 80

           = 504 /252

           = 2

    Molecular formula = n(Empirical formula)

                               = 2 ×CBr3

    The molecular formula of the compound is C2Br6.

    (iii) C2Br6 can be prepared from ethane by substitution reaction.

     

    (b)   

    Salt

    Anion

    A

    Chloride ion (Cl-)

    B

    Sulphide ion (S2-)

    C

    Nitrate ion (NO3-)

    D

    Sulphite ion (SO32-)

    E

    Carbonate ion (CO32-)

     

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