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Chemistry Date: 10th Jan 2019 Full Marks :80 Std X Time :2 Hrs -----------------------------------------------------Section 1 (Compulsory)-----------------------------------------------------------Question I. Choose the most appropriate answer:[10] (1) Which of the following is an orange coloured salt. (a) Calcium chloride None of the above. (2) (b) Zinc nitrate hexahydrate (c) Ammonium dichromate (d) In the extraction of Iron from Hematite if the gangue is acidic in nature then the flux added is:(a) Limestone (b) Sand (c) Iron (III) oxide (d) NaOH. (3) During the electrolysis of molten NaCl , which of the following does not occur. (a) Sodium ions are reduced to Sodium atoms (b) Chloride ions are oxidized to chlorine atoms (c) there is an evolution of yellowish green gas at the anode (d) It is an example of a Redox reaction. (4) In the lab preparation of Ethene if the temp is maintained at 140 C instead of 170 C the product formed is: (a) Dimethyl Ether (b) Ethyl acetate (c) Ethyl ethanoate (d) Ethoxy ethane. (5) The ratio between the molecules present in 1 g of Hydrogen and 32g of oxygen is (a) 1:1 (b) 2:1 (c) 1:2 (d) none of the above (6) Which of the following ores can be concentrated by the froth floatation process:(a) Calamine (b) Horn Silver (c) copper glance (d) Siderite. (7) Which of the following alloys is used to manufacture electric heaters and Rheostats. (a) German Silver (b) stainless steel (c) Duralumin (d) Alnico. (8) Which of the following reactions will evolve a colored gas: (a) Action of warm water on Aluminium Carbide (c) action of Lead dioxide on hot and conc. HCl (9) (10) Which of the following makes steel hard but not brittle:(a) Annealing (b) Tempering (c) Quenching (b) Action of Zinc on Ethanoic acid (d) Heating a mixture of Sal ammoniac and Ca(OH)2 (d) Leaching. In the lab preparation of HNO3 , sulphuric acid acts as a (a) Less volatile acid (b) Drying agent (c) Typical acid (d) both (a) and (b). -------------------------------------------------------------------------------------------------------------------------------------------------------- Question II. [5] (1) State your observations when:- Dilute HCl is added to Pb(NO3)2 and then heated.
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