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MOCK EXAMINATION 2017 CHEMISTRY Grade: 10 Date: 19-02-2017 Time: 2 hrs. Max.marks: 80 __________________________________________________________________________ INSTRUCTIONS: The time stated above is the time allowed for writing the examination. In addition, the first 15 minutes will be the time given for reading the question paper. This paper is divided into Section A (40 marks) and Section B (40 marks). Answer all questions from Section A and any four questions from Section B. ____________________________________________________________________ SECTION A ( 40 MARKS ) Answer ALL Questions Question 1 (a) Name the following: (i) The gas used as a reducing agent in reducing copper oxide to copper. (ii) The functional group in ethanoic acid. (iii) The metal which burns in air with a golden yellow flame. (iv) The acid which produces sugar charcoal from sugar. (v) The gas produced when excess ammonia reacts with chlorine. (b) Choose the most appropriate answer for each of the following: (i)This is not an alloy of copper. (A)Brass (B)Bronze (C)Solder (D)Duralumin [5] [10] (ii)When fused lead bromide is electrolyzed, we observe (A)A silver grey deposit at the cathode and a reddish brown deposit at the anode (B) A silver grey deposit at the anode and a greyish brown deposit at the cathode (C) A silver grey deposit at the cathode and a reddish brown fumes at the anode (D) A silver grey deposit at the anode and a reddish brown fumes at the cathode (iii) Propane has (A) 7 covalent bonds (B) 9 covalent bonds (C) 8 covalent bonds (D) 10 covalent bonds (iv)Brown ring test is used for the detection of (A)Sulphate ion (B)Sulphide ion 1 (C)Nitrate ion (D) Nitride ion (v) An example of basic salt is (A)NaCl (B)CuCl (C)Cu(OH)Cl (D)NaHSO4 (vi)The number of isomers possible for molecular C5H12 (A)2 (B)3 (C)4 (D)5 (vii)Bonding in this molecule can be understood to involve coordinate bonding. (A)Carbon tetrachloride (B) Hydrogen (C)Ammonium Chloride (D)Hydrogen Chloride (viii)Methane is collected by (A)downward displacement of water (B)upward displacement of air (C)downward displacement of air (D)None of the above (ix) The vapour density of Carbon dioxide is(Atomic mass of carbon=12,oxygen=16) (A)32 (B)16 (C)44 (D)22 (x)The ratio of number of molecules in 2g of hydrogen and 32g of oxygen is (A)1:2 (B)1:0.01 (C)1:1 (D)0.01:1 (c) Write balanced chemical equations : (i) Formation of ethane from ethene (ii) Preparation of ethene from ethyl alcohol (iii) Preparation of methanol from methane (iv) Copper sulphate from copper and conc. sulphuric acid (v) Sodium thiosulphate with dil. hydrochloric acid [5] (d) State any one observation for the following reactions: (i)Sulphur dioxide is passed through acidified potassium dichromate (ii)Warm water is added to the product formed when aluminium is burnt in a jar of nitrogen gas (iii) Ethyne is bubbled through bromine in carbon tetrachloride (iv) Ammonium hydroxide is passed through ferrous sulphate solution (v) Ammonium hydroxide is passed through copper sulphate solution [5] (e) The elements of the third period in the periodic table are Na, Mg, Al, Si, P, S & Cl. Which of these elements: (i) is most electronegative (ii) has the largest I.P (iii) is the most metallic in nature (iv) is a metalloid (v) has the highest E.A (f) State /Define the following: (i) Atomic size (ii) Atomicity (iii) Homologous series (iv)Isomerism (v) Gay Lussac s law 2 [5] [5] (g) Observe the electroplating diagram given below for electroplating an iron spoon with silver and answer the following questions: [5] (i)Identify the cathode and anode. (ii)Write the equations for the reactions at anode and cathode. (iii)What happens to anode after some time during the process. (iv)Is the choice of the electrolyte in the diagram correct? Give reason. (v)State two conditions to ensure smooth electroplating. SECTION B (Answer any FOUR questions) Question 2 (a)Copy and complete the following table: Salt Method of preparation 1)Calcium carbonate 2)Iron(III) chloride 3)Sodium sulphate 4)Zinc Sulphate [4] (b)The diagram shows an experimental setup for the laboratory preparation of a pungent smelling gas which is alkaline in nature). [5] Gas Mixture X Y i)Name the compounds (Mixture X) used in the above laboratory preparation of ammonia. ii) Write a balanced equation for the reaction. 3 iii) Name the substance used to dry the gas iv) The above gas is burnt in presence of oxygen. State the observation and give the balanced equation. v) What do you observe when this gas is passed through Nessler s reagent? (c)Name the element present in third period and group 1 of the periodic table. [1] Question 3 (a)Answer the following questions: i) What is the difference between calcination and roasting? ii) Name the process used for the concentration of sulphide ore? iii) Name a metal whose oxide is amphoteric and is reduced to metal by carbon reduction. iv) Name a metal which is liquid at room temperature. [4] (b) In extraction of copper, pure copper is obtained from its ore, copper pyrites. i) The colour of the aqueous copper sulphate, does not change during the [1] electro refining process. Why? ii)Write equations at the anode and cathode during electrolysis of aqueous solution of copper sulphate with platinum electrodes. [2] (c)Outline the equations involved in the Baeyer s process. [3] Question 4 (a)Explain the following: i)Concentrated nitric acid appears yellow when it is left standing in a glass bottle. ii)Glass apparatus is used in laboratory preparation of nitric acid. iii)Dilute nitric acid is generally considered as a typical acid but not so in reaction with metals. [3] (b)Give a balanced equation for the following conversion: i) Ethanoic acid to ethyl ethanoate ii) Calcium carbide to ethyne iii) Sodium ethanoate to methane [3] (c)Draw structural formula for following: i) Propanone ii)But-2-yne [2] (d)Distinguish ethene and ethyne using a chemical test. [2] Question 5 (a)Consider the following reaction and answer the questions below: heat (NH4)2Cr2O7 N2 (g) +Cr2O3 +4H2O(g) Calculate: i)The quantity in moles of (NH4)2Cr2O7 if 63 grams of (NH4)2Cr2O7 is heated. ii)The quantity in moles of nitrogen formed at the same time. iii)The volume in litres or dm3 of nitrogen evolved at S.T.P. 4 [1] [1] [1] iv)The mass in grams of Cr2O3 formed at the same time. [Atomic masses of H=1,N=14 ,O=16,Cr=52] [2] (b) State what would you observe when i)Washing soda crystals are exposed to atmosphere. ii)The salt ferric chloride is exposed to atmosphere. [2] (c) Identify the anions in each of the following cases: i)Compound X on heating with copper turnings and conc. sulphuric acid liberates a reddish brown gas. ii)When a solution of compound Y is treated with silver nitrate solution, a white precipitate is obtained which is soluble in excess of ammonium hydroxide solution. iii)Compound Z on reacting with barium chloride solution gives a white precipitate insoluble in dil. hydrochloric acid or dilute nitric acid. [3] Question 6 (a) In the contact process for the manufacture of sulphuric acid, give the equations for i) Conversion of sulphur dioxide to sulphur trioxide ii) Conversion of sulphur trioxide to sulphuric acid [3] (b) How dilution of concentrated acid is done?Give reason. [1] (c)i) By drawing the electron dot diagram, show the lone pair effect leading to the formation of ammonium ion from ammonia gas and hydrogen ion. ii)Define the type of bonds involved in the formation of ion. [2] [2] (d)Distinguish between Lead nitrate and Zinc sulphate using ammonium hydroxide. [2] Question 7 (a)Give the equations for the following conversion A to F. A PbSO4 [6] B Pb(NO3)2 PbCO3 F C D E Pb(OH)2 PbO (b) An acid of phosphorus has the following percentage composition: 2.47 % of hydrogen, 38.27 % of phosphorus, 59.26 % of oxygen Find he empirical and molecular formula of this acid. Given that its relative molecular mass is 162. (Atomic mass: P = 31, O= 16 and H = 1) . 5 [4]
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