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GUNDECHA EDUCATION ACADEMY FINAL PRELIMINARY EXAMINATION 2023-2024 STD X SCIENCE PAPER 2 (CHEMISTRY) (Two hours) DATE: 12/01/2024 MARKS: 80 Answers to this Paper must be written on the paper provided separately. You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the Question Paper. The time given on the head of this paper is the time allowed for writing the answers. Section I is compulsory. Attempt any four questions from Section II. 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) Choose the most appropriate answer from the choices given in each case: [15] (i) Jack wants to electroplate his spoon with silver. Which electrolyte solution is preferred for the below electroplating process? a) b) c) d) Silver chloride Silver nitrate Sodium argentocyanide Silver argentocyanide (ii) The salts formed by partial replacement of the replaceable hydrogen ion of an acid molecule by a basic radical is ________ salt. a) Acid b) Basic c) Normal d) Complex (iii) The branched chain isomer of butane C4H10 is ___________. a) n-butane b) 2,2-dimethyl propane c) 2-methyl butane d) 2-methyl propane GEA/FINAL PRELIMINARY EXAMINATION -2023-24 This paper consists of 7 printed pages Turn Over STD X CHEM (iv) -2- 2023-2024 Dry ammonia gas was passed over a black substance A as shown in the set-up below. Identify the gas B collected in the gas jar. a) b) c) d) Hydrogen Oxygen Nitric oxide Nitrogen (v) A compound X having vinegar like smell on warming with ethanol in the presence of an acid Z, gives a compound Y which has a fruity smell. The reaction is as given below, identify the reaction : Z C2H5OH + X Y + H2 O a) Catenation b) Hydrogenation c) Dehydrohalogenation d) Esterification (vi) Seema has collected (a) 2 litres of CO 2 (b) 3 litres of chlorine (c) 5 litres of hydrogen (d) 4 litres of nitrogen and (e) 1 litres of SO 2, under similar conditions of temperature and pressure. Which gas sample will have the greatest number of molecule? a) 2 litres of CO2 b) 3 litres of chlorine c) 5 litres of hydrogen d) 4 litres of nitrogen (vii) Ionization potential increases over a period from left to right because the: a) Atomic radius and nuclear charge increases b) Atomic radius and nuclear charge decreases c) Atomic radius increases and nuclear charge decreases d) Atomic radius decreases and nuclear charge increases (viii) State which is not a common characteristic of an electrovalent compound? a) High melting point. b) Conducts electricity when molten. c) Consists of oppositely charged ions. d) Ionizes when dissolved in water. GEA/FINAL PRELIMINARY EXAMINATION -2023-24 This paper consists of 7 printed pages Turn Over STD X CHEM -3- 2023-2024 (ix) An alloy which contains a non-metal as one of its constituents is _________. a) Brass b) Solder c) Stainless steel d) Duralumin (x) The mass of sodium [Na=23] which will contain 6.023 x 1023 atoms is ____ g. a) 11 b) 46 c) 11.5 d) 23 (xi) A metal which produces hydrogen on reacting with alkali as well as with acid. a) Iron b) Magnesium c) Zinc d) Copper (xii) Study the diagram alongside, which shows the Brown Ring Test. Name the radical detected. a) b) c) d) Sulphate Nitrate Chloride Ferrous (xiii) The gas produced on reaction of dilute sulphuric acid with a metallic sulphide is _____________________. a) Sulphur dioxide b) Hydrogen c) Hydrogen sulphide d) Chlorine (xiv) A Solution X with pH = 10, will show which of the following indicator tests. a) Methyl orange turns pink b) Blue litmus turns red c) Phenolphthalein remains colourless d) Phenolphthalein turns pink (xv) The drying agent used to dry hydrogen chloride gas is ___________. a) Conc. H2SO4 b) CaO c) P2O5 d) Al2O3 Question 2 a) State one relevant observation for each of the following reactions: [5] (i) Action of ammonia on excess chlorine. (ii) Ammonium hydroxide solution is added drop wise to Ferric chloride solution. GEA/FINAL PRELIMINARY EXAMINATION -2023-24 This paper consists of 7 printed pages Turn Over STD X CHEM (iii) -4- 2023-2024 Dilute hydrochloric acid is added to lead nitrate solution and the mixture is heated. Aqueous copper sulphate solution is electrolysed using copper electrodes. Action of conc. sulphuric acid on hydrated copper sulphate. (iv) (v) b) Calculate: (i) From the given equation: [2] 2NaOH + H2SO4 Na2SO4 + 2H2O Calculate how much sodium hydroxide is required to make 14.2g of sodium sulphate. [Na= 23, O= 16, H= 1, S= 32] (ii) 450 cm3 of nitrogen monoxide and 200 cm3 of oxygen are mixed together and ignited. Calculate the composition of the resulting mixture. [2] 2NO + O2 2NO2. (iii) The gram molecules in 42g of nitrogen.[N=14] [1] c) Give the appropriate term defined by the statements below: [5] (i) Process of heating the concentrated ore to a high temperature in presence of air. (ii) The amount of energy released when an atom in the gaseous state accepts an electron to form an anion. (iii) Undistilled alcohol containing large amounts of methanol in the mixture. (iv) A compound which when dissolved in water yields hydroxyl ions as the only negatively charged ions. (v) The amount of substance which contains the same number of units as the number of atoms in 12 g of carbon. d) Write a balanced chemical equations for each of the following: (i) Conversion of SO3 to oleum in the contact process. (ii) Reaction of ethanol with sodium metal at room temperature. (iii) Laboratory preparation of hydrogen chloride gas. (iv) Dehydrohalogenation reaction of bromoethane. (v) Action of cold and dilute nitric acid on copper. e) Write the IUPAC name of the following compounds: (i) [5] [2] (ii) GEA/FINAL PRELIMINARY EXAMINATION -2023-24 This paper consists of 7 printed pages Turn Over STD X CHEM -5- 2023-2024 (iii) Draw the structural formula of the following organic compounds: [3] A. 2-methyl propan-1-ol B. But-2-ene C. 2,3-dimethyl butane SECTION II (40 Marks) Attempt any four questions from this section. Question 3 a) Give a chemical test to distinguish between the following: (i) Sodium sulphate and sodium sulphite. (ii) Lead nitrate and Copper [II] nitrate. [2] b) An element X and Y has atomic number 19 and 17 respectively. [3] (i) Which element X or Y will have more ionisation potential. (ii) State the type of bonding between X and Y. (iii) Comment on the melting/boiling point of compound formed between X and Y c) Copy and complete the following equations: d) (i) NH3[excess] + Cl2 _________ + _________. (ii) (iii) (iv) Na2SO3 + HCl _________ + _________ +________. CuO + H2SO4 ________ + ________ NH3 + O2 _______ + _______ [4] Explain the term - Catenation [1] Question 4 a) Draw an electron dot diagram to show the formation each of the following : (i) Ammonia (ii) H3O+ ion b) Match the salts listed in column A with the appropriate method of preparation listed in column B: A B (i) Ferrous sulphide (a) Displacement. (ii) Zinc Sulphate (b) Neutralisation. (iii) Sodium sulphate (c) Direct Combination. . c) State the property demonstrated with respect to HCl gas by fountain experiment. d) Write a balanced chemical equations for the following conversions: A B ZnSO4 Zn (OH)2 Na2ZnO2 Question 5 [4] [3] [1] [2] a) An organic compound contains 40% carbon and 6.67% hydrogen. [4] The rest is made up of oxygen. Its vapour density is 90. Determine its empirical and molecular formula. [C=12, H= 1, O=16] GEA/FINAL PRELIMINARY EXAMINATION -2023-24 This paper consists of 7 printed pages Turn Over STD X CHEM -6- 2023-2024 b) Define: (i) Electronegativity (ii) Co-ordinate bond c) An aqueous solution of copper (II) sulphate was electrolysed using platinum electrodes. (i) (ii) (iii) (iv) [2] [4] State the change noticed in the electrolyte. State the observation at cathode. Name the product at anode. Write the reaction at cathode. Question 6 a) Answer the following questions relevant to Baeyer s process in the extraction [3] of aluminium from its chief ore, bauxite. (i) Name the solution X used to react with bauxite as a first step in obtaining pure aluminium oxide, in the Baeyer s process. (ii) State the reason for the addition of solution X to the bauxite ore. (iii) Write the equation for the reaction where the aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide. b) Write the chemical formula of the following ores: (i) Zinc blende. (ii) Haematite [2] c) Write a point of difference between the following: (i) Alkali metals and Halogens (ii) Electrovalent compounds and Covalent compounds. [2] d) Choose the correct answers from the list that matches the description below: Do not repeat the same option. [HCl, Al(OH)3, NaHSO4, CH3COOH] (i) A Monobasic acid (ii) An Acid salt (iii) A Hydracids. [3] Question 7 a) Galena, when roasted, reacts according to the following equation: 2PbS + 3O2 2PbO + 2SO2 [Pb = 207, O = 16, S= 32] (a) Calculate the weight of PbO formed when 478 g of PbS is roasted. (b) Calculate the weight of PbS required to produce 5.6 litres of SO2 at S.T.P. [2] b) State Gay Lussac s Law of combining volumes of gases. [1] c) Name the following: [4] (i) The cation present in the solution that produces reddish brown precipitate on dropwise addition of sodium hydroxide (ii) The particles present in sugar solution. GEA/FINAL PRELIMINARY EXAMINATION -2023-24 This paper consists of 7 printed pages Turn Over STD X CHEM (iii) (iv) -7- 2023-2024 An alloy of lead used in electric wiring or electrical work in joining metals. Organic compounds having the same molecular formula but differing in molecular arrangement or in structural formula. Copy and complete the following table relating to an important industrial process [3] and its final output: Name of process Contact process Inputs (Contact Tower) Catalyst Temperature Chemical equation. Sulphur dioxide + oxygen Question 8 a) Give one relevant reason for each of the following statements below: [3] (i) Pure acetic acid is called glacial acetic acid. (ii) Concentrated nitric acid appears yellow, when it is left for a while in a glass bottle. (iii) Conductivity of dilute hydrochloric acid is greater than that of acetic acid. b) Calculate the number of moles in 14 g of nitrogen. [N = 14]. [1] c) State any one use of the following: i) Duralumin ii) Acetylene [2] d) Write a balanced chemical equation for the following preparation: (i) Preparation of methane from sodium acetate. (ii) Preparation of PbCl2 from PbO. (iii) Preparation of ethyl alcohol from bromoethane. [4] GEA/FINAL PRELIMINARY EXAMINATION -2023-24 v This paper consists of 7 printed pages END
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