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GOLDCREST HIGH, LATUR PRE-BOARD EXAMINATION GRADE: 10 SUBJECT: SCIENCE PAPER-2 (CHEMISTRY) Time: 2 Hours Max. Marks: 80 Answer to this question must be written on the paper provided separately. You will not be allowed to write answers for the first 15 minutes. This time is to be spent on reading the question paper. The time given at the head of this paper is the time allotted for the writing the answer. The paper is divided into two sections. Attempt all questions from Section A and any four questions from Section B. The intended marks for questions or parts of questions are given in brackets [ ] SECTION-I (40 Marks) (Attempt all questions from this Section) Question-1 (a) The following statements are correct only under certain conditions. Rewrite each statement including appropriate conditions underlined in your answers (i) Sodium reacts with chlorine to form sodium chloride. (ii) The electrolysis of lead bromide liberates lead and bromine. (iii) Copper crystals are dehydrated by sulphuric acid. (iv) Calcium nitrate reacts with sodium sulphate to form calcium sulphate. (v) Metals of IA group are called alkaline earth metals. [5] (b) State one relevant observation for each of the following: [5] (i)When the gaseous product obtained by dehydration of ethyl alcohol is passed through bromine water. (ii)When hydrogen sulphide gas is passed through lead acetate solution. (iii)At the anode when aqueous copper sulphate solution is electrolyzed with copper electrodes (iv) Excess of chlorine gas is reacted with ammonia gas. (v)Water is added to the product formed when aluminium is burnt in a jar of nitrogen gas (c) Write balanced chemical equations for each of the following: (i) Action of hot and concentrated Nitric acid on copper. (ii)A unsaturated hydrocarbon from calcium carbide. (iii)Reduction of hot Copper (II) oxide to copper using ammonia gas. (iv)Potassium nitrate and conc. Sulphuric acid heated below 2000C. (v)Action of sodium hydroxide on aluminium oxide. [5] (d) Complete the following calculations. Show working for complete credit. [5] (i) Calculate the number of moles and the number of molecules in 6.2 g of lead nitrate. [Pb=207,N=14,O=16] (ii) How many grams of ammonia will contain the same number of molecules as 1.1g of carbon dioxide. [C=12,O=16,N=14,H=1] (iii) Define the terms relative molecular mass and molar volume PB-EX/CHE/2019/KSH This question paper consists of 5 printed pages and 1 blank page Page 1
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