ICSE BOARD PAPER-2013 Set-1 2013 Set 1

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  • Q1

    (a) Give the balanced equation for each of the following:

    (i) Reduction of hot Copper (II) oxide to copper using ammonia gas.

    (ii) Oxidation of carbon with concentrated nitric acid.

    (iii) Dehydration of concentrated sulphuric acid with sugar crystals.

    (b) Copy and complete the following table relating to important industrial process:

    (c) The following questions relate to the extraction of aluminum by electrolysis:

    (i) Name the other aluminium containing compound added to alumina and state its significance.

    (ii) Give the equation for the reaction that takes place at the cathode.

    (iii) Explain why it is necessary to renew the anode periodically.

    Marks:10
    Answer:

    (b) Temperature: 450C to 500C

    Catalyst: Finely divided iron with promoter molybdenum

    Equation:

    (a) (i) Cryolite (Na3AlF6) is the other aluminium containing compound added to alumina during its electrolytic reduction. Cryolite lowers the melting point of alumina to around 950C and makes it a good conductor of electricity.

    (iii) In the electrolytic reduction of alumina oxygen gas is liberated at anode. The evolved oxygen reacts with carbon anode to form carbon dioxide and carbon monoxide. We have to replace carbon anode periodically, as it gets oxidised.

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  • Q2

    (a) Give balanced equations for the laboratory preparations of the following organic compounds:

    (i) A saturated hydrocarbon from iodomethane.

    (ii) An unsaturated hydrocarbon from an alcohol.

    (iii) An unsaturated hydrocarbon from calcium carbide.

    (iv) An alcohol from ethyl bromide.

    (b) Give the structural formulae for the following:

    (i) An isomer of n-butane.

    (ii) 2-Propanol.

    (iii) Diethyl ether.

    (c) Give reasons for the following:

    (i) Methane does not undergo addition reactions, but ethene does.

    (ii) Ethyne is more reactive than ethane.

    (iii) Hydrocarbons arte excellent fuels.

    Marks:10
    Answer:

    (c) (i) Ethene being an alkene contains a carbon-carbon double bond. This double bond breaks and provide site for addition. On the other hand methane being saturated hydrocarbon does not undergo addition reaction.

    (ii) Due to the presence of triple bond (it acts as a site for addition reaction) ethyne is more reactive than ethane.

    (iii) Hydrocarbons burn in air to form carbon dioxide with release of a large amount of heat and light. Due to this reason, they are excellent fuel.

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  • Q3

    (a) O2 is evolved by heating KClO3 using MnO2 as a catalyst.

    (i) Calculate the mass of KClO3 required to produce 6.72 L of O2 at STP. [atomic masses of K = 39, Cl = 35.5, O = 16]

    (ii) Calculate the number of moles of oxygen present in the above volume and also the number of molecules.

    (iii) Calculate the volume occupied by 0.01 mole of CO2 at STP.

    (b) Identify the following substances which are underlined:

    (i) An alkaline gas which produces dense white fumes when reacted with hydrogen chloride gas.

    (ii) An acid which is present in vinegar.

    (iii) A gas which does not conduct electricity in the liquid state but conducts electricity when dissolved in water.

    (iv) A dilute mineral acid which forms a white precipitate when treated with barium chloride solution.

    (v) The element which has the highest ionisation potential.

    Marks:10
    Answer:

    (b) (i) Ammonia gas (NH3)

    (ii) Acetic acid (CH3COOH)

    (iii) Hydrogen chloride (HCl)

    (iv) Sulphuric acid (H2SO4)

    (v) Helium (He)

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  • Q4

    In this table H does not represent hydrogen.

    Some elements are given in their own symbol and position in the periodic table.

    While others are shown with a letter.

    With reference to the table answer the following questions:

    (i) Identify the most electronegative element.

    (ii) Identify the most reactive element of group 1.

    (iii) Identify the element from period 3 with least atomic size.

    (iv) How many valance electrons are present in Q?

    (v) Which element from group 2 would have the least ionisation energy?

    (vi) Identify the noble gas of the fourth period.

    (vii) In the compound between A and H what type of bond would be formed and give the molecular formula for the same.

    (g) (i) Compare the compounds carbon tetrachloride and sodium chloride with regard to solubility in water and electrical conductivity.

    Marks:10
    Answer:

    (a) (i) J

    (ii) R

    (iii) M

    (iv) Since element Q belongs to group 15, it contains 5 valence electrons.

    (v) T

    (vi) y

    (vii) Element A belongs to group 1 and is a metal. While, element H belongs to the group 17 and is a non–metal. The bond formed between metallic and non-metallic elements is ionic bond.

    (b) Carbon tetrachloride which is a covalent compound is insoluble in water and behaves as a bad conductor of electricity. On the other hand, sodium chloride which is an ionic compound is soluble in water and behaves as a good conductor of electricity in aqueous state.

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  • Q5

    (a) Choosing the substances from the list given below, write balanced chemical equations for the reactions which would be used in the laboratory to obtain the following salts:

    (i) Sodium sulphate

    (ii) Zinc carbonate

    (iii) Copper (II) sulphate

    (iv) Iron (II) sulphate.

    (b) State two relevant observations for each of the following:

    (i) Ammonium hydroxide solution is added to copper (II) nitrate solution in small quantities and then in excess.

    (ii) Ammonium hydroxide solution is added to zinc nitrate solution in minimum quantities and then in excess.

    (iii) Lead nitrate crystals are heated in a hard glass test tube.

    Marks:10
    Answer:

    (b) (i) Copper nitrate solution when treated with ammonium hydroxide solution gives a pale blue precipitate which dissolves in excess of ammonium hydroxide solution to give a deep blue solution.

    (ii) Zinc nitrate solution when treated with ammonium hydroxide solution gives a white gelatinous precipitate which dissolves in excess of ammonium hydroxide solution.

    (iii) A reddish-brown colour gas is evolved. When this reddish brown gas is passed through iodine solution, violet fumes are liberated.

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  • Q6

    (a) Copper sulphate solution is electrolysed using copper electrodes. Study the diagram given below and answer the question that follows:

    (i) Which electrode to your left or right is known as the oxidising electrode and why?

    (ii) Write the equation representing the reaction that occurs.

    (iii) State two appropriate observations for the above electrolysis reaction.

    Using the information above, complete the following:

    (i) ___ is the metallic element.

    (ii) Metal atoms tend to have a maximum of ___ electrons in the outermost energy level.

    (iii) Non-metallic elements tend to form ___oxides while metals tend to form ___ oxides.

    (iv) Non-metallic elements tend to be ___conductors of heat and electricity.

    (v) Metals tend to ___ electrons and act as ___agents in their reactions with elements and compounds.

    Marks:10
    Answer:

    (a) (i) The electrode on the right hand side is the oxidising electrode because at this electrode Cu2+ ions gain electrons and converted into metallic copper (Cu) i.e., reduction takes place.
    (ii)

    (iii) (A) The copper atoms deposit at cathode and the size of the cathode increases.

    (B) The size of the anode decreases and the colour of the solution remain blue.

    (b) (i) Y

    (ii) 8

    (iii) Acidic, basic

    (iv) Bad

    (v) Lose, reducing

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  • Q7

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

    [ammonia, ammonium, carbonate, carbon dioxid e, hydrogen, hydronium, hydroxide, precipitate, salt, water]:

    (i) A solution M turns blue litmus red, so it must contain (i) ___ ions; another solution O turns red litmus blue and hence, must contain (ii) ___ ions.

    (ii) When solutions M and O are mixed together, the products will be (iii) ___ and (iv) ___.

    (iii) If a piece of magnesium was put into a solution M, (v) ___ gas would be evolved.

    (b) Identify the gas evolved in the following reactions when:

    (i) Sodium propionate is heated with soda lime.

    (ii) Potassium sulphite is treated with dilute hydrochloric acid.

    (iii) Sulphur is treated with concentrated nitric acid.

    (iv) A few crystals of KNO3 are heated in a hard glass test tube.

    (v) Concentrate hydrochloric acid is made to react with manganese dioxide.

    (c) State one appropriate observation for each of the following:

    (i) Concentrated sulphuric acid is added drop wise to a crystal of hydrated copper sulphate.

    (ii) Copper sulphide is treated with dilute hydrochloric acid.

    (iii) Excess of chlorine gas is reacted with ammonia gas.

    (iv) A few drops of dilute hydrochloric acid are added to silver nitrate solution, followed by addition of ammonia hydroxide solution.

    (v) Electricity is passed through molten lead bromide.

    (d) Give suitable chemical terms for the following:

    (i) A bond formed by a shared pair of electrons with both electrons coming from the same atom.

    (ii) A salt formed by incomplete neutralisation of an acid by a base.

    (iii) A reaction in which hydrogen of an alkane is replaced by a halogen.

    (iv) A definite number of water molecules bound to some salts.

    (v) The process in which a substance absorbs moisture from the atmospheric air to become moist, and ultimately dissolves in the in the absorbed water.

    (e) Give a chemical test too distinguish between the following pairs of compounds:

    (i) Sodium chloride solution and sodium nitrate solution.

    (ii) Hydrogen chloride gas and hydrogen sulphide gas.

    (iii) Ethene gas and ethane gas.

    (iv) Calcium nitrate solution and zinc nitrate solution.

    (v) Carbon dioxide gas and sulphur dioxide gas.

    (f) Choose the most appropriate answer from the following options:

    (i) Among the period 2 elements, the element which has high electron affinity is;

    (A) Lithium

    (B) Carbon

    (C) Chlorine

    (D) Fluorine

    (ii) Among the following compounds identify the compound that has all three bonds (ionic, covalent and coordinate bond)

    (A) Ammonia

    (B) Ammonium chloride

    (C) Sodium hydroxide

    (D) Calcium chloride

    (iii) Identify the statement that is incorrect about alkanes:

    (A) They are hydrocarbons.

    (B) There is a single covalent bond between carbon and hydrogen.

    (C) They can undergo both substitution as well as addition reactions.

    (D) On complete combustion they produce carbon dioxide and water.

    (iv) Which of these will act as a non electrolyte?

    (A) Liquid carbon tetrachloride

    (B) Acetic acid

    (C) Sodium hydroxide aqueous solution

    (D) Potassium chloride aqueous solution

    (v) Which one of the following will not produce an acid when made to react with water?

    (A) Carbon monoxide

    (B) Carbon dioxide

    (C) Nitrogen dioxide

    (D) Sulphur trioxide

    (vi) Identify the metallic oxide which is amphoteric in nature:

    (A) Calcium oxide

    (B) Barium oixide

    (C) Zinc oxide

    (D) Copper (II) oxide

    (vii) In the given equation identify the role played by concentrated sulphuric acid:

    (A) Non-volatile acid

    (B) Oxidising agent

    (C) Dehydrating agent

    (D) None of the above

    (viii) Nitrogen gas can be obtained by heating:

    (A) Ammonium nitrate

    (B) Ammonium nitrite

    (C) Magnesium nitride

    (D) Ammonium chloride

    (ix) Which of the following is not a typical property of an ionic compound?

    (A) High melting point.

    (B) Conducts electricity in the molten and in the aqueous solution state.

    (C) They are insoluble in water.

    (D) They exist as oppositely charged ions even in the solid state.

    (x) The metals zinc and tin are present in the alloy:

    (A) Solder

    (B) Brass

    (C) Bronze

    (D) Duralumin

    (g) Solve the following:

    (i) What volume of oxygen is required to burn completely 90 dm3 of butane under similar conditions of temperature and pressure?

    (ii)The vapour density of a gas is 8. What would be the volume occupied 24.0 g of the gas at STP?

    (iii) A vessel contains X number of molecules of hydrogen gas at a certain temperature and pressure. How many molecules of nitrogen gas would present in the same vessel under the same conditions of temperature and pressure?

    Marks:40
    Answer:

    (a)

    (i)Hydronium

    (ii)Hydroxide

    (iii) Salt

    (iv) Water

    (v)Hydrogen

    H
    (b)
    (i)
    Ethane (C2H6)

    (ii) Sulphur dioxide (SO2)

    (iii) Nitrogen dioxide (NO2)

    (iv) Oxygen (O2)

    (k) Chlorine (Cl2)

    (c) (i) Concentrated H2SO4 dehydrates copper sulphate crystals into anhydrous copper sulphate crystals, changing them from blue to white.

    (ii) Hydrochloric acid reacts with copper sulphide to form copper chloride liberating H2S gas which has the smell of rotten egg.

    (iii) When excess of chlorine gas is treated with ammonia gas, a yellow coloured explosive is formed.

    (iv) A curdy white precipitate of silver chloride is formed, which is soluble in ammonium hydroxide solution.

    (v) On passing electricity through molten lead bromide, reddish brown vapours of bromine are evolved at anode.

    (d) (i) Coordinate bond.

    (ii) Acidic salt.

    (iii) Halogenation reaction.

    (iv) Water of crystallisation.

    (v)Deliquescence.

    (e) (i) Sodium chloride when treated with silver nitrate solution forms a curdy white precipitate of AgCl which is soluble in ammonium hydroxide solution. Sodium nitrate solution does not give this test.

    (ii) On adding few drops of silver nitrate solution hydrogen chloride gas produces a white precipitate of silver chloride. Whereas no such precipitate is formed in case of hydrogen sulphide gas.

    (iii) Ethene gas decolorises the purple colour of KMnO4 solution, whereas no such change is observed with ethane gas.

    (iv) Aqueous calcium nitrate when treated with NaOH solution gives a thick white precipitate which remains insoluble in excess of NaOH. Aqueous zinc nitrate when treated with NaOH solution gives a white gelatinous precipitate which dissolves in excess of NaOH.

    (v) When carbon dioxide gas is passed into lime water, the lime water turns milky. Sulphur dioxide gas does not turn lime water milky.

    (f) (i) (D)

    (ii) (B)

    (iii) (C)

    (iv) (A)

    (v) (A)

    (vi) (C)

    (vii) (B)

    (viii) (C)

    (ix) (C)

    (x) (C)

    (iii) We know that, equal volume of all gases under the same conditions of temperature and pressure contains equal number of molecules. Hence, the number of molecules of nitrogen gas will also be X.

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