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GOLDCREST HIGH, LATUR ON THE WINGS OF EXCELLENCE CYCLE TEST-1 FOR CLASS X (2018-19) SCIENCE PAPER-2 (CHEMISTRY) TIME: 1 HOUR 15 MINUTES F.M: 50 Answer to this paper must be written on the paper provided separately. You will not be allowed to write during the first 10 minutes. This time is to be spent in reading the Question Paper. The time given at the head of this paper is the time allowed for writing the answers. The intended marks for the questions or parts of the questions are given in brackets [ ]. Question 1 (a) Starting from lead nitrate, how will you prepare the following salts in laboratory? Write only the balanced chemical equations in support of your answer. (i) Lead chloride (ii) Lead sulphate (iii) Lead carbonate (iv) Lead sulphide [4] (b) How are the following conversions carried out? Give balanced chemical equations only (Fig: 1) [3+3=6] (Fig: 2) (c) Write balanced chemical equations for the following. (i) Nitric acid reacts with metal to produce hydrogen (ii) Nitric acid reacts with metal to produce nitrogen dioxide. (iii) Nitric acid reacts with metal to produce nitric oxide (iv) Nitric acid reacts with carbon to form carbon dioxide. [4] Question 2 (a) Explain the terms (i) Electrochemical series (ii) Selective discharge of ions [2] (b) Al 3+, Cu2+,Na1+,Zn2+ ,OH-,Br-,SO42- ions are present in an aqueous solution, such that the concentration of ions are same. Write the order of discharge of ions by giving reasons. [2] CHE/CT-1/2018-19/KSH This question paper consists of 3 printed pages Page 1 (c) Give appropriate scienctific reason for the following: [5] (i)The ratio of hydrogen and oxygen formed at the cathode and anode is 2:1 by volume on electrolysis of water (ii)Why is alternating current not used during electrolysis? (iii) The blue colour of the electrolyte remains unchanged during electrolysis of CuSO4 soln. with copper as electrode. Why? (iv) How does lead bromide ionize in water when water is a polar covalent compound? (v) The blue colour of the electrolyte fades during electrolysis of CuSO4 soln. with platinum as electrode. Why? (b) Copy and complete the following table related to electrolysis. S.N O 1 NAME OF THE ELECTROLYTE H2O (acidified) NAME OF CATHODE Platinum foil NAME OF ANODE Platinum foil 2 CuSO4 (aq) Copper Carbon 3. Sodium silver cyanide (aq) Spoon Silver block [3] REACTION AT CATHODE REACTION AT ANODE Question 3 (a) Give appropriate scienctific reason for the following: (i)Why the electric bulb glows up once the concentration of the aluminium falls down in the elctrolytic chamber in the Hall s Heroult process. (ii)The anode is replaced periodically in the Hall s Heroult process.Why? (iii) Pure alumina is not directly electrolysed in the Hall s Heroult process.Why? (b) Giving one example, explain the following terms used in the metallurgy: [3] [5] (i)Calcination (ii) Roasting (iii) Gangue (iv) Flux (v) Slag (c) For each substance listed below explain its significance in the extraction of aluminium: [5] (i) Bauxite (ii) Sodium Hydroxide (iii) Cryolite (iv) Fluorspar (v) Graphite (d) Write the composition and uses of the following alloys mentioned below: [5] Steel, Duralumin, Brass, Bronze, Solder CHE/CT-1/2018-19/KSH This question paper consists of 3 printed pages Page 2 (f) Aluminium is extracted from its chief ore, bauxite. The ore is first purified and then metal is extracted from its by electrolytic reduction (i)Write the balanced reaction for the conversion of impure bauxite to impure alumina. [2] (ii)Complete the table NAME OF THE PROCESS [4] ELECTROLYTE USED AND ITS DISSOCIATION REACTION REACTION AT CATHODE REACTION AT ANODE PRODUCT AT CATHODE PRODUCT AT ANODE 1. HALL S HEROULT PROCESS 2. HOOPE S PROCESS CHE/CT-1/2018-19/KSH This question paper consists of 3 printed pages Page 3
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