10 – Chemistry – ICSE 2011 Set 1

To Access the full content, Please Purchase

  • Q1

    (a) Differentiate between electrical conductivity of copper sulphate solution and copper metal.        [3 marks]
    (b) Sodium hydroxide solution is added to the solution containing the ions mentioned in List X. List Y gives the details of the precipitate. Match the ions with their coloured precipitates.

    List X

    List Y

    (i)

    Pb2+

    A.

    Reddish brown

    (ii)

    Fe2+

    B.

    White insoluble in excess

    (iii)

    Zn2+

    C.

    Dirty green

    (iv)

    Fe3+

    D.

    White soluble in excess

    (v)

    Cu2+

    E.

    White soluble in excess

    (vi)

    Ca2+

    F.

    Blue

                                                                  [3 marks]
    (c) During the electrolysis of copper (II) sulphate solution using platinum as cathode and carbon as anode:

    (i) What do you observe at the cathode and at the anode?                                      [1 marks]

    (ii) What change is noticed in the electrolyte? [1 marks]


    (iii) Write the reactions at the cathode and at the anode.                                                          [2 marks]

                                                                     

    Marks:10
    Answer:

    (a) Difference between electrical conductivity of copper sulphate solution and copper metal:

    Copper sulphate 

    Copper metal

    (i)


    (ii)



    (iii)

    Electrical conductivity is due to flow of ions.

    It conducts electricity in aqueous solution or in molten state.

    It decomposes and undergoes chemical change.

     

    (i)


    (ii)



    (iii)

    Electrical conductivity is due to flow of electrons.

    It conducts electricity in solid state.

    It does not undergo chemical change.

           

    (b)

    List X

    List Y

    (i)

    Pb2+

    D.

    White soluble in excess

    (ii)

    Fe2+

    C.

    Dirty green

    (iii)

    Zn2+

    E.

    White soluble in excess

    (iv)

    Fe2+

    A.

    Reddish brown

    (v)

    Cu2+

    F.

    Blue

    (vi)

    Ca2+

    B.

    White insoluble in excess

     

    (c)
    (i) A shiny metal (copper) deposits at cathode and at anode, bubbles of a colourless odourless gas (oxygen) are seen.
    (ii) The colour of electrolyte gradually fades from blue to colourless.
    (iii) 

    View Answer
  • Q2

    (a) Answer the following question:
    (i) Name a metal which is found abundantly in the earth’s crust.
    (ii) What is the difference between calcination and roasting?
    (iii) Name the process used for the enrichment of sulphide ore.
    (iv) Write the chemical formulae of one main ore of iron and aluminium.
    (v) Write the constituents of electrolyte for the extraction of aluminium.                        [5]

    (b) The diagram shows an experimental set up for the laboratory preparation of a pungent smelling gas. The gas is alkaline in nature. 

    (i) Name the gas collected in the jar.
    (ii) Write the balanced equation for the above preparation.
    (iii) How is the gas being collected?
    (iv) Name the drying agent used.
    (v) How will you find that the jar is full of gas?  [5]

    Marks:10
    Answer:

    (a) (i) Aluminium
    (ii) Calcination is the heating of concentrated ore in the absence of air where as roasting is the heating of concentrated ore in excess of air.
    (iii) Froth floatation process
    (iv) Main ore of iron  haematite – Fe2O3
    Main ore of aluminium
    Bauxite – Al2O3. 2H2O
    (v) Molten alumina + cryolite + fluorspar

    (b) (i)
    Ammonia
    (ii) 
    (iii) It is collected in gas jar by downward displacement of air.
    (iv) Quick lime (CaO)
    (v) By bringing a wet red litmus paper near the brim
          (mouth) of the gas jar. If the jar is full of ammonia     
           gas, the litmus paper will turn blue.

    View Answer
  • Q3

    (a) An organic compound with vapour density = 94 contains
    C= 12.67%, H=2.13% and Br 85.11%. Find the molecular formula. [Atomic mass :C=12, H=1,Br =80] [3 marks]
    (b) Calculate the mass of

    (i) 1022 atoms of sulphur.
    (ii) 0.1 mole of carbon dioxide.
    [Atomic mass: S = 32, C = 12 and O = 16 and Avogadro’s Number = 6 x 1023]                 [2 marks]
    (c) In the laboratory preparation of hydrochloric acid, HCl gas is dissolved in water.
    (i) Draw a diagram to show the arrangement used for the absorption of HCl in water.
    (ii) Why is such an arrangement necessary?  Give two reasons.
    (iii) Write the chemical equations for the laboratory preparation of HCl gas when the reactants are:
    (A) Below 200
    °C      (B) Above 200°C                [5 marks]

    Marks:10
    Answer:

    (a)


    (b)



    (c) (i) 

    (ii)
    (A) This arrangement is necessary to check back suction of water into the apparatus.
    (B) It provides larger surface area for hydrogen chloride gas.

    (iii)
     

    View Answer
  • Q4

    (a) Choose the correct word/phrase from within the brackets to complete the following sentences:
    (i) The catalyst used for conversion of ethene to ethane is commonly ……………(nickel/iron/cobalt).
    (ii) When acetaldehyde is oxidised with acidified potassium dichromate, it forms ……… (ester/ethanol/acetic acid).
    (iii) Ethanoic acid reacts with ethanol in presence of concentrated H2SO4 so as to form a compound and water. The chemical reaction which takes place is called …………
    (dehydration/hydrogenation/esterification)
    (iv) When 1, 2- dibromoethane and alcoholic potassium hydroxide react with each other, they form …………. (ethane, ethene, ethyne)
    (v) The product formed when ethene gas reacts with water in the presence of sulphuric acid is ………… (ethanol/ethanal/ethanoic acid).          
     [5 marks]

    (b) Write balanced chemical equations for the following:
    (i) Monochloro ethane is hydrolysed with aqueous KOH.
    (ii) A mixture of soda lime and sodium acetate is heated.
    (iii) Ethanol under high pressure and low temperature is treated with acidified potassium dichromate.
    (iv) Water is added to calcium carbide.
    (v) Ethanol reacts with sodium at room temperature.                                       [5 marks]

    Marks:10
    Answer:

    (a)

    (i) nickel

    (ii) acetic acid

    (iii) esterification

    (iv)  ethyne

    (v) ethanol

    (b)

    View Answer
  • Q5

    (a) (i) With the help of equations, give an outline for the manufacture of sulphuric acid by contact process.
    (ii) What property of sulphuric acid is shown by the reaction of concentrated sulphuric acid when heated with
    (A) potassium nitrate (B) carbon?               [5 marks]
    (b) (i) What is the special feature of the apparatus that is used in the laboratory preparation of nitric acid?
    (ii) Why should the temperature of the reaction mixture of nitric acid not be allowed to rise above 200
    °C?                                                             [2 marks]
    (c) Write balanced chemical equations for the following:
    (i) Chlorine reacts with excess of ammonia.
    (ii) Ferric hydroxide reacts with nitric acid.
    (iii) Zinc oxide dissolves in sodium hydroxide.  [3 marks]
     

    Marks:10
    Answer:

    (a)
    (i) The various steps in the contact process are as follows.

    (ii)
    (A) Non-volatile nature 
    (B) Oxidising property

    (b)
    (i) Complete apparatus is made of glass.
    (ii) The temperature of the reaction should not exceed 200°C because sodium sulphate formed at higher temperature forms a hard crust that sticks to the walls of the retort and is difficult to remove. At a temperature higher than 200°C, nitric acid decomposes.
    (c)

    View Answer
  • Q6

    (a)
    (i) Give the number of group and period of the element having three shells with three electrons in valence shell.
    (ii) By drawing an electron dot diagram, show the lone pair effect leading to the formation of ammonium ion from ammonia gas and hydrogen ion.
    (iii) What happens to the crystals of washing soda when exposed to air? Name the phenomenon exhibited. [5 marks]

    (b) Name the method used for preparation of the following salts from the list given below:
    (i) Sodium nitrate (ii) Iron (III) chloride
    (iii) Lead chloride  (iv) Zinc sulphate
    (v) Sodium hydrogen sulphate                       
    List :
    (A) Simple displacement  (B) Neutralisation
    (C) Decomposition by acid (D) Double decomposition
    (E) Direct synthesis                                 [5 marks]   
     

    Marks:10
    Answer:

    (a)     
    (i)Group 13, Period 3
    (ii)

    (iii) 
    When crystals of washing soda are exposed to air, they lose their water of crystallisation and become amorphous. This phenomenon is called efflorescence. 

    (b)

    (i) Neutralisation

    (ii) Direct synthesis

    (iii) Double decomposition

    (iv) Simple dispalcement

    (v) Decomposition by acid

    View Answer
  • Q7

    (a) Choose from the following list of substances as to what matches the description from (i) to (v) given below:
    [Acetylene gas, aqua fortis, coke, brass, barium chloride, bronze, platinum]
    (i) An aqueous salt solution used for testing sulphate radical.
    (ii) A catalyst used in the manufacture of nitric acid by Ostwald’s process.
    (iii) A black powdery substance used for the reduction of zinc oxide during its extraction.
    (iv) A gaseous hydrocarbon commonly used for welding purposes.
    (v) The substance is an alloy of zinc, copper and tin.                                                                  [5 marks]
     

    (b) What would you observe in each of the following cases?
    (i) Ammonium hydroxide is first added in a small quantity and then in excess to a solution of copper sulphate.
    (ii) Sugar crystals are added to a hard glass test tube containing concentrated sulphuric acid.
    (iii) Copper is heated with concentrated nitric acid in a hard glass test tube.
    (iv) Water is added to the product formed, when aluminium is burnt in a jar of nitrogen gas.
    (v) When carbon monoxide is passed over heated copper oxide.                                              [5 marks]

    (c) Give reasons as to why:
    (i) the electrolysis of acidulated water is considered to be an example of catalysis.
    (ii) almost 90% of all known compounds are organic in nature.
    (iii) it is dangerous to burn methane in an insufficient supply of air.
    (iv) hydrogen chloride can be termed as a polar covalent compound.
    (v) the oxidising power of elements increases on moving from left to right along a period in the periodic table.                                                                                     [5 marks]
    (d) Fill in the blanks from the choices given below:
    (i) In covalent compounds, the bond is formed due to the  ………………… (sharing/transfer) of electrons.
    (ii) Electrovalent compounds have a ……………………. (low/high) boiling point.
    (iii) A molecule of ……………………. contains a triple bond. (hydrogen, ammonia, nitrogen)
    (iv)Across a period, the ionization potential ……………………. (increases, decreases, remain same)
    (v) Down the group, electron affinity ……………………. (increases, decreases, remains same)                                                                       [5 marks]

    (e) (i) Calculate the volume of 320 g of SO2 at STP. (Atomic mass: S = 32 and O = 16)
    (ii) State Gay-Lussac’s Law of combining volumes.
    (iii) Calculate the volume of oxygen required for the complete combustion of 8.8 g of propane (C3H8). (Atomic mass: C = 14, O = 16, H = 1, Molar Volume = 22.4 dm3 at STP)                            [5 marks]

    (f) Choose the correct answer from the options given below:
    (i) This metal is a liquid at room temperature.
    (A) Potassium           (B) Zinc

    (C) Gold                    (D) Mercury

    (ii) Hydroxide of this metal is soluble in sodium hydroxide solution.

    (A) Magnesium         (B) Lead

    (C) Silver                  (D) Copper

    (iii) In the periodic table, alkali metals are placed in the group
    (A) 1                          (B) 11

    (C) 17                 (D) 18

    (iv) Hydrogen chloride gas being highly soluble in water is dried by:
    (A) Anhydrous calcium chloride  (B) Phosphorous penta oxide

    (C) Quick lime    (D) Concentrated sulphuric acid

    (v) The brown ring test is used for detection of:
    (A) CO2-3            (B) NO-3

    (C) SO2-3             (D) Cl-                                                      

     

    (vi) When dilute sulphuric acid reacts with iron sulphide, the gas evolved is …………….
    (A) Hydrogen sulphide   (B) Sulphur dioxide

    (C) Sulphur trioxide        (D) Vapour of sulphuric acid

    (vii) The functional group present in acetic acid is:
    (A) Ketonic > C = O (B) Hydroxyl - OH

    (C) Aldehydic – CHO       (D) Carboxyl – COOH

    (viii) The unsaturated hydrocarbons undergo:

    (A) A substitution    (B) An oxidation reaction

    (C) An addition reaction (D) None of the above

    (ix) The number of C – H bonds in ethane molecule are:
    (A) Four       (B) Six

    (C) Eight      (D) Ten

    (x) Which of the following properties do not match with elements of the halogen family?
    (A) They have seven electrons in their valence shell.
    (B) They are highly reactive chemically.
    (C) They are metallic in nature.
    (D) They are diatomic in their molecular from. [10 marks]

    (g) Write a balanced chemical equation for each of the following reactions:

    (i) Sodium thiosulphate is reacted with dilute hydrochloric acid
    (ii) Calcium bicarbonate reacts with dilute hydrochloric acid
    (iii) Dilute sulphuric acid is poured over sodium sulphite
    (iv) Lead nitrate solution is added to sodium chloride solution
    (v) Zinc is heated with sodium hydroxide solution
    [5 marks]

    Marks:40
    Answer:

    (a)

    (i) barium chloride           

    (ii) platinum

    (iii) coke                          

    (iv) acetylene

    (v) brass

    (b) 

    (i) First a pale blue precipitate is formed on addition of ammonium hydroxide, which becomes soluble in excess of ammonium hydroxide, resulting in formation of deep blue solution.

    (ii) Sugar crystals turn into a black spongy mass. Steam and heat are evolved during the reaction.
    (iii) A reddish brown pungent smelling gas (nitrogen dioxide) evolves.
    (iv) When aluminium is burnt in a jar of nitrogen gas, aluminium nitride is formed. Aluminium nitride reacts with water, curdy white precipitate of aluminium hydroxide is formed and pungent smelling ammonia gas is formed.
    (v) Black powdery copper oxide changes to red shiny copper metal and carbon monoxide gas is evolved.

    (c)

    (i) During electrolysis of acidulated water, the quantity of acid remains unchanged and the rate of electrolysis of water is increased. Therefore, the electrolysis of acidulated water is considered as an example of catalysis.
    (ii) About 90% of all known compounds contain carbon and hydrogen, and are obtained from or are present in the living world, plants and animals. Therefore, almost 90% of all known compounds are organic in nature.
    (iii) When methane is burnt in insufficient supply of air, carbon monoxide is formed. Since it is poisonous in nature, it is dangerous to burn carbon monoxide in an insufficient supply of air.
    (iv) There is large difference between electronegativities of hydrogen and chlorine. Therefore, hydrogen chloride can be termed as polar covalent compound.
    (v) The oxidising power of an element depends on ease of accepting electron, which is measured in terms of electron affinity. As we move from left to right in periodic table, the tendency to accept electron increases (electron affinity) and therefore, the oxidising power increases on moving from left to right along a period in the periodic table.

    (d)

    (i) sharing          

    (ii) high
    (iii) nitrogen       

    (iv) increases

    (v) decreases

    (e)(i)

     

     

    (ii)
    Gay Lussac’s Law of combining volumes:
    When gases react together to form gaseous products and all volumes are measured at same temperature and pressure, then the ratio between the volumes of the reacting gases and the gases produced bear a simple whole number ratio to each other.                                                         

    (iii)

     

    (f)
    (i)
    (D) Mercury   
    (ii) (B) Lead
    (iii) (A) 1
    (iv) (D) Concentrated sulphuric acid
    (v) (B) NO-3
    (vi) (A) Hydrogen sulphide
    (vii) (D) Carboxyl – COOH
    (viii) (C) an addition reaction
    (ix) (B) Six
    (x) (C) They are metallic in nature. 

    (g)

    View Answer