Formatting page ...
KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 Time Allowed: Two hours Date: _________ ANSWER KEY SECTION A (Attempt all questions from this Section.) Question 1 Choose the correct answers to the questions from the given options. [15] (Do not copy the question, write the correct answers only.) i. ii. iii. iv. v. vi. vii. viii. ix. x. xi. xii. xiii. xiv. xv. (d) Only Q (b) Nitrogen dioxide (a) Both M and N (c) It turns red (b) Oxidizing nature (b) the electrolyte must contain ions of the base metal to be electroplated. (d) Ferric hydroxide (b) X (a) Green (d) 19 (c) 1:3 (a) Butanal (b) Reduction (d) Mo (d) Group 16 Question 2 i. Complete the following sentences by choosing the correct answers from the brackets: (a) Largest (b) Phosphoric acid (c) Chalky (d) Alkynes (e) Acidic [5] KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 Time Allowed: Two hours Date: _________ ii. The setup shown below is that of the fountain experiment with ammonia gas in the flask. [5] (a) Due to its high solubility in water, thereby creating a partial vacuum in the flask. (b) The fountain will be blue in colour. Since ammonia is basic in nature and base turns red litmus blue. (c) Yes, there will be a different observation and the red litmus will remain red since acid does not change the color of red litmus. iii. Match the following Column A with Column B. Column A (a) Calcium oxide (b) Ammonia (c) Water (d) Froth Flotation (e) Conc. Sulphuric Acid [5] Column B 4. Electrovalent compound 3. Haber s Process 1. Covalent Bond 5. Sulphide ore 2. Dehydrating agent iv. Identify the following: (a) Electrovalency (b) Basicity of an acid (c) Hydrocarbons (d) Nuclear Charge (e) Ore [5] v. [5] (a) Draw the branched structural formula for the following compounds: 1. 2,2-Dichloro Butane KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 2. 2-Pentyne 3. Propanoic acid (b) Time Allowed: Two hours Date: _________ Give the IUPAC name of the following organic compound: 1. Butan-1-al / Butanal 2. Prop-1-ene / Propene SECTION B (Attempt any four questions from this Section.) Question 3 i. Compound Z MgSO3 MgSO3 + 2HCl MgCl2 + H2O + SO2 [2] ii. What property of ammonia is exhibited in each of the following cases: a) Basic Nature b) Reducing action [2] iii. The electronegativity of element X is greater than that of element Y. a) More b) Less c) Y is placed on the left of X [3] KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 Time Allowed: Two hours Date: _________ iv. (a) State whether the following statement are TRUE or FALSE. Justify your answer: [2] 1. False, M is non-metallic in nature. 2. False, Shared pair of electrons is two. (b) Weight 64 15 = No of Molecules = 6 x 1023 = (15 x 6 x1023 ) / 64 = 1.406 x 1023 [1] Question 4 i. The following questions relate to the extraction of Aluminium: [2] a) Conc. Solution of sodium hydroxide b) Prevents burning of carbon electrodes and minimizes the heat loss by radiation. ii. 35 g of a gas forms 15,000 cm3 of vapours at STP. Calculate the molecular weight of the gas. 35 = 15000 ? = 22400 [2] (35 x 22400) / 15000 = 52.26 g iii. Write the balanced chemical equation for each of the following: a) 200 C NaNO3 + Conc. H2SO4 NaHSO4 + HCl Pt b) 4NH3 + 5O2 800 C 4NO + 6H2O + c) Dehydrohalogenation of 1,2-Dibromo ethane with alcoholic potassium hydroxide. [3] KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 Time Allowed: Two hours iv. With respect to Contact Process answer the following: a) Vanadium pentoxide / Platinum b) 450 500 C c) SO3 + H2SO4 H2S2O7 Date: _________ [3] Question 5 i. Ethan wants to differentiate between sulphur dioxide gas and hydrogen [2] sulphide gas in the laboratory. He has been given moist lead acetate paper. a) Sulphur dioxide Hydrogen sulphide Gas is exposed to moist lead Gas is exposed to moist lead acetate paper acetate paper No characteristic reaction Paper turns silvery black / black b) Rotten Egg odour. ii. Name the alloy which is having the following metals as its main component: [2] a) Duralumin b) Stainless steel iii. Dany takes a white powdered salt W in a test tube. On heating it produces a buff yellow residue. W is dissolved in water. Magnesium is added to one part of the solution and to the other part sodium sulphate solution is added. [3] a) Compound W Lead nitrate b) Magnesium nitrate. c) PbSO4 iv. State scientific reasons for each of the following statements: [3] a) They have the tendency to make oily products on treatment with halogens. b) Since there is an elimination of carbon dioxide molecule from a carboxylic acid. c) Since the reaction is exothermic. Question 6 i. Name the following: [2] a) The main ore of iron - haematite b) The ore of aluminium containing sodium Cryolite / Sodium aluminium fluorine. KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 Time Allowed: Two hours Date: _________ ii. State one observation in each of the following: a) Greenish yellow chlorine gas evolved. b) Curdy white ppt of Silver chloride. [2] iii. Acidified water is electrolysed using platinum electrode. a) Cathode b) For accurate comparison and saturation of gases. c) OH1- -1e- OH x 4 4OH 2H2O + O2 [3] iv. X [2, 8, 5] and Y [2, 8, 3] are two elements. Using the information complete the following: [3] a) Lose b) X c) X Question 7 i. The empirical formula of an organic compound is CHCl2 and its molecular weight is 168. Find the molecular formula. [Atomic weights; C-12; H-1; Cl-35.5] [3] EF = CHCl2 EFW = 84 n = 168 / 84 = 2 MF = C2H2Cl4 ii. Joel prepared a solution R that has a pH 7. What will be the effect on the pH on addition of the following? a) pH will increase b) pH will decrease iii. Fluorine iv. 12.6g of Copper oxide is obtained on thermal decomposition of copper carbonate. CuCO3 CuO + CO2 Calculate the following: a) Mass of copper carbonate initially taken. Copper oxide = Copper carbonate 79 = 123 12.6 = (12.6 x 123) / 79 = 19.617 [2] [1] [4] KARNATAKA ICSE SCHOOLS ASSOCIATION ICSE STD. X Preparatory Examination 2024 Subject: CHEMISTRY (SCIENCE PAPER 2) Maximum Marks: 80 b) Time Allowed: Two hours Date: _________ Volume of carbon dioxide at STP. Weight 79 12.6 = = = Volume 22.4L (12.6 x 22.4) / 79 = 3.527 L Question 8 i. Differentiate between the following on the basis of the parameters given in the brackets: [2] a) Ferrous sulphate and ferric chloride (Sodium hydroxide solution) Ferrous sulphate Ferric Chloride On addition of sodium hydroxide On addition of sodium hydroxide solution solution Dirty green ppt, Insoluble in Reddish brown ppt, insoluble in excess excess b) Acidic and alkaline solutions (addition of sodium carbonate) Acidic solutions Alkaline solution Addition of Sodium carbonate Addition of Sodium carbonate Carbon dioxide not evolved Carbon dioxide not evolved ii. Draw the electron dot structure for ammonium ion. [2] iii. Write the balanced chemical equation for the following: [3] a) Mg3N2 + 6H2O 3Mg(OH)2 + 2NH3 b) C2H5OH + CH3COOH CH3COOC2H5 + H2O [Conc Sulphuric acid mention above the arrow] c) 2C2H6 + 7O2 4CO2 + 6H2O + iv. Identify the following: [3] a) Anode b) Hydrogen sulphide c) Monobasic acid
|
