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LOKHANDWALA FOUNDATION SCHOOL PRELIMINARY EXAMINATION-2020-21 SUBJECT-CHEMISTRY Date: 29/01/21 Grade: 10 Duration: 2 Hrs. Max. Marks: 80 _____________________________________________________________________________________ Instructions:-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 given time at 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 [ ]. The paper consists of 6 sides. _______________________________________________________________________________________ SECTION I (40 marks) (Attempt all questions from this section) Q1. a) Choose the correct answer from the options given below: [5] i. The element having highest electron affinity from the following elements is A. Bromine B. Chlorine C. Fluorine D. Iodine ii. From the given list, identify the covalently bonded compound. A. Magnesium chloride B. Sodium chloride C. Carbon tetrachloride D. Lead chloride iii. In the electrolysis of acidified water, sulphuric acid acts as a A. Catalyst B. Non- volatile acid C. Dehydrating agent D. An Oxidising agent iv. In the organic compound ethene, contain Carbon atoms joined byA. Single covalent bond B. Double covalent bond C. Triple covalent bond D. None of the above v. The basic gas ammonia shows colour change from orange to yellow, the indicator used is A. Alkaline phenolphthalein B. Phenolphthalein C. Litmus solution D. Methyl orange Grade: 10 b. Match the following. S. No. i ii iii iv v Subject: Chemistry Column I Acetic acid Sulphuric acid Methane neo- pentane Ethanal S. No. A B C D E Page no. 2 [5] Column II Dimethyl propane Marsh gas Acetaldehyde Ethanoic acid Oil of vitriol c. Fill in the blank using the options given in the bracket. [5] In the (i.) ________(thermal /electrolytic) decomposition of acidified water, the electrode used is a/an (ii.) ______ (active / inactive) in which (iii.) _____ (hydrogen / oxygen) is evolved at anode and (iv.) _______ (hydrogen / oxygen) is evolved at cathode. In this process, the (v.) _______(reduction / oxidation) takes place at cathode. d. Write balanced chemical equation for the following conversions along with conditions if any. i. Calcium carbonate to calcium chloride ii. Ammonia to nitrogen iii. Ethene to 1,2- dichloroethane iv. Copper oxide to copper sulphate v. Ethane to Carbon dioxide [5] e. Give reason for the following. [5] i. Sodium chloride exists as crystalline hard solid. ii. In electro-refining of copper using active electrode, the cathode gains weight. iii. Ammonia gas is not collected over water. iv. Ethane undergoes substitution reactions. v. Aqueous HCl is monobasic in nature. f. Differentiate between the following on the basis of the criteria given in the bracket. i. Sodium sulphate and Sodium sulphite (BaCl2 Solution) ii. Copper chloride and Zinc chloride (Aqueous NaOH) iii. Ferrous sulphate and Ferrous sulphide (Moist lead acetate paper) iv. Oxygen and Water (Type of covalent compound) v. Sodium and Chlorine (Atomic size) [5] Grade: 10 Subject: Chemistry Page no. 3 g. Elements X, Y and Z have atomic number 11, 17 and 18 respectively. [5] Answer the following questions based on it. i. Write the electronic configuration of X and Y. ii. If X and Y combine to form a compound, it will have low melting and boiling point. State True or False. iii. Compound XY will conduct electricity in (solid/ fused) state. iii. State the position of Z in the Modern periodic table. iv. Draw the electron dot structure of Y2 molecule. h. A compound has the following percentage composition by mass: [5] Carbon 85.71%, Hydrogen 14.29%. i. Determine the Empirical formula of this compound. (H=1, C=12) ii. If the vapour density of the hydrocarbon is 35, what is its molecular formula? iii. Is it a saturated or unsaturated hydrocarbon? SECTION II (40 marks) (Attempt any four questions from this section) Q 2. a. Ammonia is prepared in the laboratory. i. Write the balanced equation along with conditions if any. ii. Name the drying agent used. iii. After the collection of gas, how is it identified? iv. Ammonium nitrate is not used as a reactant. Justify. [4] b. Name the following. i. A greenish yellow gas. ii. A non- metal which is a conductor of electricity. iii. An oxide which is yellow when hot and white when cold. iv. The property of carbon to form chain or ring structure. [4] c. Draw the structural diagram of the following organic compounds. i. Butan-2-ol ii. 2- methyl propane [2] Grade: 10 Subject: Chemistry Page no. 4 Q 3. a. With respect to the electrolysis of molten lead bromide, answer the following questions. i. Why is lead bromide maintained in molten state? ii. Why is the electrolytic cell made up of silica? iii. State the reaction taking place at cathode. iv. What do you observe at anode? [4] b. State the conditions only for the following reactions. i. Conversion of aluminium hydroxide to aluminium oxide. ii. Laboratory preparation of hydrogen chloride gas. iii. Industrial preparation of ammonia by Haber s process. iv. Hydrogenation of ethylene. [4] c. Draw the electron dot diagram of i. H3O+ ii. CaO [2] Q 4. a. Answer the following questions based on Modern periodic table. [3] i. The alkali metals have ________ (high/ low) ionisation potential. ii. Define electron affinity. iii. Which element among the following elements from period 3 will have high electro negativity. Magnesium, Chlorine, Sodium, Phosphorus b. In the extraction of aluminium by Hall- Heroult's processi. Name and state the formula of the ore used. ii. Name the components added to the above ore for the electrolytic process. iii. Why the electrolyte is covered with coke? iv. Name the gas evolved at anode. [4] c. Write a balanced chemical equation to show the following properties of concentrated Sulphuric acid. i. Oxidation of Sulphur. ii. Dehydrating agent with hydrated copper sulphate crystals. iii. Non- volatile nature in the preparation of nitric acid. [3] Grade: 10 Subject: Chemistry Page no. 5 Q 5. a. Write balanced chemical equations for the following. i. Dilute HCl reacts with sodium sulphite solution. ii. Dilute sulphuric acid is added to granulated zinc. iii. Chlorination of methane. iv. Ammonium chloride is heated with sodium hydroxide. [4] b. State the term used for[4] i. Uniform deposition of superior metal over a baser metal. ii. The tendency of an element to attract electrons towards itself in a compound. iii. The bond formed between a metal and a non- metal. iv. Type of covalency in which one of the combining atom contributes both the shared electrons. c. Draw the structural diagram of position isomers of butene. [2] Q 6. a. State any one observation for the following. i. A pinch of copper carbonate is heated in a dry test tube. ii. Lead nitrate is heated in a dry test tube. iii. Silver nitrate is added to sodium chloride solution followed by NH4OH. [3] b. Answer the following questions when a spoon is to be coated with silver metal. [4] i. Write the dissociation reaction of the electrolyte used. ii. A low current is passed for a longer period of time. Justify. iii. Write the observation at anode. iv. Write the reaction at cathode. c. Write the IUPAC names of the following structures. i. ii. [3] iii. Grade: 10 Subject: Chemistry Page no. 6 Q 7. a. Answer the following. [4] i. Find the molecular weight of Ethene. [H=1, C=12] ii. Find the vapour density of ethene. iii. Name the next alkene after ethene in the homologous series. iv. Ethene undergoes bromination in presence of an inert solvent CCl4. Write the IUPAC name of the product formed. b. Copy and complete the table relating to the important industrial process. Output of the process refers to the final product of the process and not the intermediate step. Name of the process Inputs Catalyst [4] Equation for the catalysed Output reaction Nitric acid c. Choose the correct option from the following. [2] i. An aqueous solution of nickel sulphate will contain__________(ions only/ ions and molecules) ii. Ammonium hydroxide when added to salt solution of _________ (Ca 2+ / Pb2+) does not form any precipitate. *********************************************
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