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KES Kohinoor International School SECOND PRE BOARD EXAMINATION 2024- 2025 GRADE-10 SUBJECT: - Chemlstry STUDENT'S NAME DATE - 13-01-2025 ROLL NO. TIME -2 HOURS MAXIMUM MARKS - 80 Answers to this Paper must be writt "n on the paper provided separately. Yoxu vill nc be cllovwed to wIite during the first 15 minutes. This timc is to bo spent inreading the Question Paper he tinc givcn ot the head of this paper is the time allowed for writing the answers. Section Ais compulsory. Attempt any four questions from Section B. The intended nerks jor questions or parts of questions are given in brackets [] SICTION A (Ai:mpt olla.e.tio:s fro:n this section) Qucstion 1 oSe the correct a sers to tt:e questions iroin the given options. (15] only. ) Onot copy the question, write lLhe correct aiiswers from one atom to . ASsertion : Atoms can combine either by transter of valence electrons another or by sharing valence electrons. have an octet in their Reason : Sharine and transfer of valence electrons IS done by atoms to valence shel statements and reason is the correct a. Assortion and reason both are correct ex!anaticn of the assertion. statements, but reason is not the b. Assertion ard reasonbotn are correct assertion. corrcct explanation ofthc but the reason is ialse . C. 4ssertion is true. reason is true. C. scricn is false, but the ii. Electroplating is a process in which thin film of metal like gold, silver, nickel etc. gets deposited. Which of the observation shows correct combination with respect tT electroplating of silver on a brass spoon: Anode Cathode W Spoon Electrolyte Pure silver X Pure silver Spoon Spoon Na[Ag(CN)] Na[Ag(CN),] Pure silver [Ag(CN),] Pure silver Spoon AgNO, iii. The chemical name of bauxite ore is: a. Aluminium oxide b. Sodium aluminium fluoride C. Hydrated alumirium oxide ! d. None of these iv. As tt.e pH ofthe solution 8. Increases decreases, its acidic strength progressively b. Decreases . Does not change d. Depends on the quantity of solution V. Salts of nornnal elements [ 1 (|A) to 17 (VIl A) ]are generally. a. Colourless b. Green C. White d. Plue 2 vi. 10g of magnesium carbonate reacts with excess dilute hydrochloricacid. What volume of carbon dioxide is completely formed at room temperature and pressure ? |Mg= 24, C= 12,O= 16] The equation for the reaction is: MgCO, + 2HCI MgCl, + H,0 + a. 2.8 dm CO, b. 2.6 dm C. 2.2 im3 d. 2.4 dm vii. In the laboratory, hydrogen chloride is prepared by action of conc. sulphuric acid on sodium chloride. Which of the following statement is correct with respect to the above statemnent. P:Gas is collected by the downwarddisplacement of air in a gas jar. Q:It is dried by passing through CaO. a. Only P b. Neither Q c. Neiher P nor a d. Both P and Q vii. Thecompounds Aand Bin the given reactioi, respectively ,are: 2KHCO, A B+ 2h,0 +2C0, a. H,SO, and KHSO, b. 4,S and KiHSO, C. H,CO, and K,CO, d. H,SO, and K,SO, ix. A comnpound P is heated in a test tube with sodium hydroxide solution. Ared litnus paDer held at the mouth of the test tube turns blue. Which of the following could compound P be ? a. Zinc sulphate b. Copper sulphate . Ferrous sulphate d. Ammonium sulphate x. Element 'S' has electronic (2,8,8.1) In its compound with chiorine, how may chlorineconfiguration atoms are ? present a. 2 b. 1 . 3 d. 4 xi Which of the following ofganic compounds is of tbenzene A Conpound A b. Compound B c. Compound C d Compounds B and C xii Which of the following would occupy 22.4 itres at S.I.P ? 1. 32 g of oxygen gas 2. 2 moles of hydrogen gas 3. 6.023 x 10 molecules of ammonia a. 1 and 2 b l and 3 C 2 and 3 d. 1, 2and 3 xii. Cn passing amimonla gas over heated copper oxide for some time, reddish brown residue is left behind. What property of ammonia is demonstrated here ? a. Basic property b. Oxidising property C. Reducing property d. Acidicproperty xiv. Which ofthefollowing statements describes the properties of amphoteric oxides? a. They react with acids to form salts and water. b. They react with bases to form salts and water. h yexhibit both acidic and basic properties, reacting with both acids and }ases. c. They do not react with acids or bases. occupied by 4.4 grams of carbon XV. The ratio between the volumes dioxide ard 2 grarns of hydrogen gas is : . 2.2:1 b. 1:2.2 . 1:10 d. 10:1 (Question 2 I. Analyse the given (5) questions: diagram and answer the following Dry NH, Combustion tube <N, gas Cold water 2. Which oxide is depicted property of the metal in the above diagram ? b. C. What is taken in the combustion tube ? Enlist your observations if the compound taken in CuO (ii) PbO (Also give combustion tube is () d. Give the function of coldequations) water. ii. Match the following Column Awith Column B ColumnA Column B a)Neon Ammonium ion b)Methane c) Ammonia d) An ion e) i) gas in water witha lone pair Aweak electrolyte Hydronium ion ii) Magnesium hydroxide of electrons. iv) Non - polar covalent v) Zero clectron affinity compound ii. Complete the following by choosing the correct irom the compound that does not have a lone pairanswers of electrons is bracket: (S1 ammonia/ carbon tetrachloride). (water/ a. The b. Arnmonia reacts with excess chlorine to trichloride/ ammonium chloride) c. Il a d. The form (nitrogen/ nitrogen hydrocarbon has the formula of Cso Hgg then it is likely to a/an (addition/ undergo (saturated/ substitution) reaction, and the hydrocarbon is a/an unsaturated hydrocarbon) number of hydrogen atoms present in 1 mole of sulphuric acid and 1 mole of sulphurous acid are () and (Y) and Y is respectively: (X= Y/ cannot compare Xand Y) Reiationship between % iv. Identify the following : a. Name the alikyi component of acetic acid. h ldentify the longest carbon chain and mention the present in it. (S) number of carbons C. An alkali that forms a strong base when d. The type of gas. dissolved in water. bonding found between the atoms in a molecule of hydrogen e. A gas used in the Ostwald process for the production of nitric acid. V. a. Draw the structura! diagram for the following compounds: 1. Marsh gas 2. 2,3- dimetiyl butane 3. Ethanal b. Give the IUPAC name of the fol!owing organic compounds : 1. -H H- 2) 2 -H H dine thyl Propne H -H H H 2. H H H- . PYopanorc acid OH 7 (5] SECTIONB (Attempt any four questions ) Question 3 i. Platinum catalyst is used in the catalytic oxidation of ammonia. Writean equation for the reaction that occurs in the above case. b. Why does the platinum continue to glow even after the heating is discontinued ? 2] a. ii. C,H, 200C X [2] Given above is the representation of the conversion of ethene to a saturated hydrocarbon X, where 'a' stands for the catalyst. a. ldentify 'a' b. Give the ii. With complete chemical equation for the conversion of C,H, to X reference to the first three periods of the modern periodic table, answer the questions given below: (3] a. Write the formula of the sulphate of the element with atomic number 13. b. Name the element which has the highest ionisation potential. C. What is the name given to the energy released when an atom in its isolated gaseous state accepts an electron toform an anion ? iv. Following chemicai equation is given : 2NH,CI + Ca(OlH), CaCl, + 2H,0 + 2NH, [N= 14, E=1, Ca =40, O= 16, Cl= 35.5 ] [3] a. Calculate the mass of ammonia obtained from 321g of ammonium chloride. b. Fird the mass of ammonium chloride required to obtain 6 moles of H,0. C. Find the mass of ammonium chloride required to obtain 4 moles of NH, Question 4 TOUare provided with the list of chemicals mentioned in the box: (3) Sodium hydroxide solution, copper carbonate, zinc, hydrochloric acid, copper, dilute sulphuric acid, chlorine, iron Using suitable chemicals from the list given,,write balanced chemical equation for the preparation of the salts mentioned below: a. Copper sulphate b. Sodium zincate "C. Ferric chloride i.The following questions relate to the extraction of Aluminium by electrolysis. (2) a. Narne the other aluminium containing compound added to alumina and state its significance. b. Expiain why it is necessary to renew the anode periodically. with 7.0 iii. Ravi heated 18.0 grams of compound X ( molecular weight 360) compound. grams of compound Y(molecular weight 140) to form anew by Ravi. Determine the empirical forrnula of the compound obtained following: iv. Give balanced chemical equations for each of the chlorine. a. Reaction of excess ammonia with using chlcroethane and aqueous b. Laboratory preparation of ethanol by sodium hvuroxide. . Rezctionof copper with concentrated nitric acid. (2] (3] Question 5 i. To an acid prepared by the contact State one observation and write an process, Barium chloride solution is added. equation for the reaction. (2) ii. Name the alloy which is made up of : a. Aluminium and b. Iron, Nickel, [2] Magnesium. Chromium, Carbon. ii. Astudent prepared a Potassium sulphite solution in the lab and added few drops of barium nitrate solution to it. He observed a white precipitate being formed in the test tube. On addition of dilute hydrochloric acid to the white precipitate and mixing it, he observed that the precipitate disappeared. a. Name the white b. Write a precipitate. balanced chemical eguation for the reaction between dilute hydrochloric acid and the white precipitate. [3] C. Name the gas evolved in the above reaction. iv. This is aschematic illustration showing the separation method of impurities from ore in Column A. Choose the appropriate answers from column B to match the portions designated A, Bard C. [3] ColuntnA Column B 1. Non-magnetic impurities 2. Magnelic ore 3. Magnetic roller 4. Nonmagnetic roller A 5. Powdered ore 3 Question 6 . tiement yforrm:s an oxide with the formula Y,0,, which is a volatile liquid at room temperature, Based on this information,which of the following elements is likely to form this Oxide ? (2] 1. (a) Carbon (b) Phosphorus (c) Sulphur (d) Sodium 2. Justify your answer in the above question (1) ii. The description of an organic compound is as follows : [2] a. Molecular formula is C,H,0. b. Functional group is attached to the first carbon atom. c. Reacts with sodium at room temperature with brisk cffervescence, releasing hydrogen gas. ldentify the compound and draw its structure. i . Seema takes a blue crystalline salt P ina test tube. On heating it produces a part of the white anhydrous powder. P is dissolved in water. Zinc is added to one is added. [3] solution and to another part of the solution barium chloride a. Name the compound P the solution of P. b. Mention one observation when zinc is added to chloride is added to c. State the colour of the precipitate formed when bariun the solution of P. brackets: iv. Fill in the blanks from the choices given in the a. (3) Whensodium chloride is heated with concentrated sulphuric acid below 20o C. (sodium hydrogen sulphate/ sodium one of the products formed is sulphate /chlorine). b ISulphuric acid/ Hydroch!oric acid) does not form ar acid salt. is (zinc/ platinum) C. The catalyst used in the oxidat1o:f arimonia i . Draw the electron i . balanced acid a. giving Lead with Zinc b. i.State Question 8C. b. 2. idertify 1Mn, Copper 1Methare . Caloulate b. a. MasVoluTe grams 12 D. WE Wil Question 7 LPrIye (3) (2] 2] [3) [4) 3) Which to thes dilute and nitrate t h e t h e turn prosue releese rezts of the of soitions of of carbonate reasons tMagnesium of ges saltsulphuric carbon equations sodiumfoloing undergoes ofzinc the 2NaNO,+O, sodium and orygen 21N3tN0, w th ethanol evoved dot solution. with methy hydrogen Silver GH if white with nitrate diagram conoentrated nitrite gas : is dilute for : acid. can and heated. complete in orange nitrate concentrated sulphuric acid. from precipitate obtained gas the each formed. decomposes be sulphuric with I of bromoethane.following: when distinguished ammonium can indicator of combustion. pt 12 HC. the at [ be Na= reacted when values STP. follcwing acid distinguished by red. 23, reacted to heating of ion. N= with by produce 3. 8 heating reactions. 14,0 zinc and with according by metal. hydrogen 10 the 16] = barium adding respectively. metal to hydrochloric chloride. gas. powder C. b. a.Give Reactior Preparation Reaction IV. Tne structures of six organic compounds are shown: H H H (3] H H H O-H H H--c--H H--H H H H of the same a. ldentify two of the compounds that are members homologous series but not isomers. of each other ? b. Vwiich two compounds are isomers equation forthe reaction. c. B can be prepared from D. Give a chemical 13
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