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CBSE Class 10 Pre Board 2026 : Chemistry (R. N. Podar School CBSE, Santacruz West, Mumbai) : Prelim

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INDIAN EDUCATION SOCIETY MANIK VIDYAMANDIR ICSE Secondary (2025-26) Std: X Date: 09/ 01/2026 PRELIMINARY EXAMINATION CHEMISTRY Marks: 80 Time: 2 Hours 1. Answers to this Paper must be written on the paper provided separately. 2. You will not be allowed to write during first 15 minutes. 3. This time is to be spent in reading the question paper. 4. The time given at the head of this Paper is the time allowed for writing the answers. 5. Section A is compulsory. Attempt any four questions from Section B. 6. The intended marks for questions or parts of questions are given in brackets [ ]. 7. This paper consist of 8 printed pages SECTION A (40 Marks) (Attempt all questions from this Section.) Question 1 Choose the correct answers to the questions from the given options. (Do not copy the question, write the correct answers only.) (i) During electrolytic conduction there is/are : (a) No new product/s are formed. (c) No transfer of electrons [15] (b) Transfer of electrons (d) No transfer of matter (ii) During electro-refining ,on electrolysis of the impure metal: (a) Pure metal is obtained at anode. (b) Pure metal is obtained at cathode. (c) Pure metal is obtained at cathode and impurities settle down. (d) Pure metal is obtained at cathode and anode becomes thick. (iii) In the laboratory preparation of ammonia ,round bottom flask is kept in an inclined position: (a) To provide maximum surface area for reaction. (b) To prevent ammonia from escaping. (c) The water vapour formed may not trickle back and crack the hot flask. (d) To speed up the rate of the reaction. (iv) Alkynes are more reactive than alkenes : (a) Alkynes contain only single bonds. (b) Alkenes undergo substitution reactions more easily. (c) Due to the presence of acetylenic linkage. (d) Alkynes react faster because carbon atoms are closer together. (v) Assertion (A): Yeast contains enzyme invertase. Reason (R): Invertase ferments glucose to ethanol. (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true and R is not the correct explanation of A. (c) A is true but R is false. (d) A is true but R is false. 1 of 8 (vi) Liquid ammonia is used as a refrigerant as(a) It is non-volatile in nature (b) It easily liquefies under pressure, and at low temperatures. (c) It has high boiling point. (d) It releases heat when it evaporates. (vii) The acid which cannot act as an oxidizing agent is ___. (a) Concentrated HCl (b) Concentrated HNO3 (c) Conc.H2SO4 (d) Dilute HNO3 (viii) (ix) (x) The metal whose oxide which is amphoteric ,is reduced to metal by carbon reduction: (a) Pb (b) Mg (c) Al (d) Fe The empirical formula of a compound is CH and its vapour density is 13 then its molecular formula will be?[ C=12,H=1] (a) C4H4 (b) C3H3 (c) C2H2 (d) CH A tribasic acid from the following: (a) H2SO4 (c) H3PO4 (b) Al(OH)3 (d) Ca(OH)2 (xi) The tendency of an atom to attract electrons to itself when combined in a compound is known as: (a) Electro-negativity (b) Electron affinity (c) Ionization potential (d) Non-metallic character (xii) Elements A and B have electronic configuration 8 and 13 respectively. The chemical formula formed between A and B will be: (a) AB (b) B3A3 (c) A2B3 (d) B2A3 (xiii) Assertion (A): Nitric acid, hydrochloric acid and acetic acid cannot form an acid salt Reason (R): They contain only one replaceable hydrogen ion. (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. (xiv) The acid that renders aluminum and iron passive is: (a) Concentrated hydrochloric acid (b) Fuming nitric acid (c) 1% dilute and cold nitric acid (d) Sulphuric acid (xv) The acid which is least volatile is: (a) Hydrochloric acid. (c) Dilute sulphuric acid (i) (b) Nitric acid. (d) Concentrated sulphuric acid. Question 2 Select the correct answer from the brackets and complete the following statements. [5] (a) (b) Brass is an alloy of ______.[ Copper and tin / Copper and zinc] The divalent metal whose oxide is reduced to metal by electrolysis of fused salt is__________ [Al/Na/Mg/K] 2 of 8 (c) (d) (e) During electrolysis the compound _____ in its molten state liberates reddish brown fumes at the anode [NaCl /PbBr2 ] Conversion of sodium acetate to methane is an example of ___________[dehydrohalogenation /decarboxylation When acetaldehyde is oxidized with acidified potassium dichromate, it forms ______. (ester / ethanol / acetic acid) (ii) Identify the following: [5] (a) Carbon-carbon double bond is called as: (b) The gas that burns in excess of air with a brilliant white flame evolving heat: (c) A mineral from which the metal can be extracted economically and conveniently is known as: (d) The alkyl component of acetic acid: (e) The type of salt formed when potassium nitrate is heated at a suitable temperature with concentrated sulphuric acid for the preparation of nitric acid in the laboratory. (iii) Draw the dot and cross structure of the following: (a) The formation of hydronium ion. [Atomic number: O=16 ,H=1 ] [2] (b) Define the term co-ionic bond. [1] (c) An ionic compound formed when calcium combines with oxygen. [Atomic number: O=16 ,Ca=20 ] [2] (iv) Match Column A with Column B . Column A [5] Column B (a) Dehydrohalogenation 1. Benzene (b) Bromo-ethane to ethanol 2. Na3AlF6 (c) Neon 3. Alcoholic KOH (d) Cryolite 4. Zero electron affinity (e) Aromatic compound 5. Aqueous KOH 3 of 8 (v) (a) Give the IUPAC name of the following organic compounds: 1. [5] 2. (b) Draw the structural diagram for the following organic compounds: 1. 2-Iodo-2-methyl propane 2. 2-Pentyne 3. Butanal SECTION B (40 Marks) (Attempt any 4 questions) (i) Question 3 Solve the following : (a) Gas M occupies a volume of 1000 c.c. and contains X molecules. How many molecules will be present in gas N occupying a volume of 250 c.c.? (b) The empirical formula of a hydrocarbon is C2H3.The hydrocarbon has a relative [2] molecular mass of 54. (At Wt: H = 1, C = 12). What is the molecular formula of the hydrocarbon? (ii) (iii) (iv) (i) Calculate the following: [2] (a) 360 g of water is how many moles of water? ( At.Wt. H=1 ,O=16) (b) How many moles of magnesium phosphate Mg3 (PO4)2 will contain 0.25 moles of oxygen atoms? Answer the following questions pertaining to the industrial manufacture of an [3] acid by Ostwald s process (a) Name the acid that is prepared by the above process. (b) Give a balanced equation for the reaction occurring into the catalytic chamber. (c) Give reason why the absorption chamber is packed with quartz in layers. State the property of the indicated component of the following alloys that makes it suitable for its use. (a) Magnesium in alloys of Aluminium. (b) Carbon in stainless steel. (c) Tin in solder. Question 4 Give one equation each to show the following properties of sulphuric acid: (b) Acidic property. (a) Dehydrating property. [3] [2] 4 of 8 (ii) Distinguished between the following pair of compounds using the reagent given in the bracket (a) Dilute hydrochloric acid and dilute sulphuric acid (using lead nitrate solution) (b) Unsaturated and saturated hydrocarbons (type of reaction they undergo) (iii) Give one significant observation when: [3] (a) Ethanoic acid is treated with sodium bicarbonate. (b) Action of heat on mixture of manganese dioxide and concentrated hydrochloric acid. (c) Concentrated sulphuric acid is added to sugar crystals. (iv) With respect to the Hall Heroult s process related to the extraction of aluminium justify the following: (a) Powdered Coke is sprinkled over the electrolytic mixture undergoing electrolytic reduction. (b) Graphite anodes are continuously replaced during the electrolysis. (c) Cryolite and fluorspar must be added to the electrolytic mixture. (i) Question 5 Draw an isomer of the following organic compounds. (a) [2] [3] [2] 2-Methyl propane (b) 1-Pentene (ii) Write balanced equations for the reactions occurring [2] in the following cases: (a) Passing dry ammonia gas over heated lead oxide placed in a combustion tube to produce a silvery grey metal. (b) Calcium nitride reacting with warm water. (iii) Nita's father bought a basket of ripe mangoes. [3] While opening it she found a small sachet containing a white crystalline powder along with the mangoes. She was told that it is a chemical that releases a gas Y which when comes in contact with moisture, induces ripening of fruits. (a) (b) Name the chemical powder in the sachet. Name the gas Y. 5 of 8 (c) Draw the structural diagram of the final product obtained when the gas Y reacts with chlorine. (iv) (i) An element X combines with oxygen to form an oxide X2O3. This oxide is a [3] good conductor of electricity and can be reduced to its metal only by electrolysis. (a) Write the equation for the reaction formed when the oxide (X2O3) combines with hydrochloric acid. (b) How many valence electrons are present in the outermost shell of X? (c) Will element X undergo oxidation or reduction? Question 6 To the acid prepared by the contact process, Barium chloride solution is added. (a) State one observation. (b) [2] Write an equation for the reaction that occurs. (ii) Explain the acidic and monobasic nature of Hydrochloric acid. (iii) Akash was given a white coloured salt Z for analysis. [3] On strong heating, the salt produced: A yellow residue when hot which turned white on cooling, A colourless gas, and a coloured gas that turned moist potassium iodide (KI) paper reddish-brown. (a) (b) (c) (iv) (i) [2] The aqueous solution of salt Z , when treated with sodium hydroxide solution, formed a white precipitate which dissolved in excess sodium hydroxide to give a colourless solution. Name the coloured gas evolved when Akash heated the salt strongly. Which cation was present in the sample given to Akash? Identify the salt given to Akash for analysis. Study the table given below. Use only the letters given in the table to answer the questions. Do not identify the elements. (a) Name the element that exhibits catenation. (b) Arrange D, G, P in increasing order of metallic character. (c) Which element is the most metallic? [3] Question 7 Calculate the following: [2] 3 (a) A gas cylinder of capacity 20 dm is filled with gas Y, the mass of which is 10 when the same cylinder is filled with the hydrogen gas at the same temperature and pressure the mass of the hydrogen is 2 g. Find the relative molecular mass of the gas. 6 of 8 What volume of ethyne gas is required to produce 8.4 dm 3 of carbon dioxide at S.T.P. 2C2H2 +5O2 4CO2 +2H2O [Atomic weight H=1,C=12,O=16] Manisha was asked to perform two experiments in the laboratory. [2] (b) (ii) (a) Based on the instructions given, observe the picture shown below and state one observation each for Experiment 1 and Experiment 2 that you would notice on mixing the given solutions. In both experiments, the reagents were first added dropwise and then in excess. Experiment 1. (b) Experiment 2. (iii) A compound P contains zinc ,sulphur ,oxygen and hydrogen only. [3] The percentage of zinc ,sulphur ,oxygen and hydrogen are 22.65 % , 11.15% ,61.32% and 4.88% respectively. The relative molecular mass of P is 287.Find the molecular formula of P assuming that all the hydrogen in the compound is present in combination with oxygen as a water of crystalization.[At. Wt.:Zn=65,S=32,O=16,H=1] (iv) V, T and U are three elements with atomic numbers 6, 17 and 18 respectively. [3] Answer the following questions using only the alphabets given. Do not identify the elements. (a) Can combine with hydrogen to form a gas which produces dense white fumes with a glass rod dipped in ammonia solution. (i) (b) Has zero electron affinity. (c) Can form a covalent compound with hydrogen atoms? Question 8 Answer the following questions: (a) Name the method used to concentrate sulphide ores. (b) Give the principle of the method identified by you. [2] 7 of 8 (ii) You are provided with the list of chemicals mentioned below : [2] [sodium hydroxide, copper oxide, aluminium , hydrochloric acid, copper, dilute sulphuric acid] Using suitable chemicals from the list given, write balanced chemical equation for the preparation of the salts mentioned below: (iii) (a) Sodium aluminate. (b) Copper sulphate. From the equation C +2H2SO4 (a) (b) (iv) CO2 + 2SO2 +2H2O Calculate : The mass of carbon oxidized by 49 g.of sulphuric acid [C=12 ,RMM of H2SO4= 98] The volume of SO2 and CO2 measured at S.T.P. liberated at the same time. With reference to the reaction occurring in the given figure: - (a) [3] [3] Identify the anode and the cathode used in the experiment and state the material from which each electrode is made. (b) Write the ionic reaction at the cathode. XXXX 8 of 8

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