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Mercy Memorial School, Kanpur Class: X Pre-board Examination 2022 -23 Date:06-02-2023 CHEMISTRY MM-80 Time: 2 Hrs. (SCIENCE PAPER-2) 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 at the head of this Paper is the time allowed for writing the answers. This question paper is divided into two sections. Section A is compulsory. Attempt any four questions from Section B. The intended marks for questions or parts of questions are given in brackets [ ]. SECTION A (40 marks) (Attempt all questions from this section) Question 1 Choose one correct answer to the questions from the given options: i. ii. iii. iv. [15] If the molecular formula of an organic compound is C10H18, it is a) Alkene b) Alkyne c) Alkane d) Not a hydrocarbon Which of the following statements is correct regarding HCl a) It is covalent both in aqueous solution and in gaseous state. b) It is covalent in the gaseous state but ionic in aqueous solution. c) It is ionic both in gaseous state and in aqueous solution. d) It can not be liquified. A gas released upon treating Zn with dil. Nitric acid a) Hydrogen b) Nitric oxide c) Nitrogen dioxide d) Nitrous oxide In the given equation identify the role played by conc. sulphuric acid C+2H2SO4 CO2+2H2O+2SO2 a) Non volatile acid b) Reducing agent c) Dehydrating agent v. vi. vii. viii. ix. x. xi. xii. xiii. d) Oxidising agent Black residue is obtained on thermal decomposition of a) Sodium nitrate b) Zinc nitrate c) Lead nitrate d) Copper nitrate Propane has a) 7 covalent bonds b) 8 covalent bonds c) 10 covalent bonds d) 9 covalent bonds Brown ring test is used for the detection of a) Nitrate ion b) Sulphate ion c) Sulphite ion d) Chloride ion Drying agent used to dry NH3 is a) P2O5 b) CaO c) Conc. H2SO4 d) Ca(NO3)2 Which of the following is insoluble in ammonium hydroxide a) Cu(OH)2 b) AgCl c) Zn(OH)2 d) Pb(OH)2 Which of the following is not an ore of aluminium a) Bauxite b) Corundum c) Epsomite d) Cryolite The catalyst used in the Ostwald s process a) V2O5 b) Pt c) Mo d) Finely divided Fe Number of lone pair of electrons in a molecule of HCl a) 3 b) 2 c) 4 d) 5 On moving from left to right across a period, ionisation potential a) Increases b) Remains same c) Goes up and down d) Decreases xiv. xv. Which of the given does not belong to the same homologous series? a) C3H8 b) CH4 c) C2H6 d) C4H8 Sodium bisulphide on reacting with dil. HCl releases ______ gas. a) Cl2 b) H2S c) SO2 d) SO3 Question 2 (i) The figure given below illustrates the apparatus used in the laboratory preparation of nitric acid. [5] (a) Name A (a liquid) and B (a solid). (Do not give the formulae) (b) Write an equation to show how nitric acid undergoes decomposition. (c) Why nitric acid prepared in the lab is yellow in colour? (d) Why is the mixture of reactants should not be heated very strongly above 200 C? (ii) Match the following column A with Column B. [5] Column A Column B (a) NaCl 1. Increases (b) Ammonium ion 2. Covalent bond (c) Electronegativity across the period 3. Ionic bond (d) Electron affinity down the group 4. Covalent and coordinate (e) Carbon tetra chloride 5. Decreases (iii) (iv) Complete the following by choosing the correct answers from the bracket:[5] a) On reaction with manganese (IV) oxide, concentrated hydrochloric acid produces a __________ [reddish brown/greenish yellow] coloured gas. b) Most common ore of iron is _______. (bauxite/haematite) c) The organic compound having a triple carbon-carbon covalent bond is________[C3H6/C3H4] d) Nitric acid is manufactured by _________. [Ostwald s process/Contact process] e) An electrolyte which completely dissociates into ions is______ [Acetic acid/Potassium hydroxide] Identify the following: [5] a) The acid which is prepared by catalytic oxidation of ammonia. b) Minerals from which metals can be extracted easily and economically. c) An alloy made by copper and zinc only. d) In electrolysis of CuSO4 solution using Pt electrodes, gas produced at anode. e) Group of hydrocarbons which will not decolourise bromine water. (v) a) Draw the structural formula for the following: 1. But-2-yne 2. Ethanoic acid 3. 2-methyl propanal b) Name the following organic compounds in IUPAC system: 1. 2. CH2Cl C C CH2 CH2Br [3] [2] SECTION B (40 marks) (Attempt any four questions from this section) Question 3 (i) Draw the electron dot structure for the following [3] a) Ammonium ion b) Magnesium chloride c) Water (ii) Salts A, B and C undergo following reactions. Identify the anion present [3] in each of these salts on the basis of these reactions: a) When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric acid, is formed. b) Addition of dilute hydrochloric acid to B produces a gas which turns lead acetate paper black. c) When a freshly prepared solution of ferrous sulphate is added to a solution of C and concentrated sulphuric acid is gently poured from the side of the test-tube, a brown ring is formed. (iii) Distinguish between the following pairs on the basis of what is given in the brackets: (iv) [2] a) Dil. HCl and dil. H2SO4 (using lead nitrate solution) b) Ferric chloride and zinc nitrate (using a weak alkali) Arrange the following as per the instructions given in the brackets: a) Na, K, Cl, S, Si (increasing order of ionization energy) b) Br, F, I, Cl (decreasing order of atomic size) [2] Question 4 (i) State the relevant observation for each of the following: a) Ethene is bubbled through a solution of bromine in carbon [3] tetrachloride. b) At anode, during electrolysis of fused PbBr2 using graphite electrodes. c) The colour of the solution left behind after electrolysis of aqueous copper sulphate solution using copper electrodes. (ii) Fill in the blanks with the correct words from the brackets: Alkenes are the (a)________(analogous/homologous) [3] series of (b)________(saturated/unsaturated) hydrocarbons. Alkenes mainly undergo (c)__________ (addition/ substitution ) reactions. (iii) Convert the following: a) Ethyne to 1,1,2,2-tetrachloro ethane b) Ethyl alcohol to ethene (iv) [2] [2] a) Write a balanced chemical equation for the complete combustion of ethane. b) Explain why ammonium nitrate is not used in the preparation of ammonia? Question 5 (i) (ii) The following questions refer to the electrolytic reduction of alumina: [3] a) Write the reaction taking place at cathode. b) Why anode needs to be replaced from time to time? c) What is the role of cryolite in this process? Calculate the empirical and molecular formula of the compound having following percentage compositionC=25.96 , H=2.22 ,0=71. 19 .Its vapour density is 45. [At. wt. of C=12, H=1, O=16] [3] (iii) Identify the substance underlined in each of the following: a) [3] The electrode that increases in mass during the electroplating of silver. b) An indicator which tuns pink in alkaline solution and colourless in an acid solution. c) (iv) The second homologue of alkyne. Define acid salt. [1] Question 6 (i) X, Y and Z are the elements in the third period of the periodic table.X forms an acidic oxide, Y forms a basic oxide and Z forms an amphoteric oxide. a) [3] Arrange the elements X, Y and Z in the increasing order of their atomic numbers. (ii) (iii) b) Name the most metallic element. c) Z belongs to which group? Give balanced equations for the following: a) Phosphorus is treated with conc. HNO3. b) Cu turnings are heated with conc. H2SO4. c) Lab preparation of hydrogen chloride gas with conditions. [3] Mention the property of conc.H2SO4 exhibited in each of the following reactions with: a) Sugar b) Metallic chloride (iv) [2] [2] a) Explain why ammonia is not collected over water? b) Name two final products formed when chlorine is reduced in excess of ammonia gas. Question 7 (i) Solution P has a pH of 13, solution Q has a pH of 6 and solution R [3] has pH of 2. Which solution- (ii) (iii) (iv) a) Will give dirty green precipitate with ferrous sulphate solution? b) Is a strong acid? c) Contains molecules as well as ions? With reference to contact process, answer the following: [3] a) Name the chemical used to remove arsenic impurities. b) Why vanadium pentoxide is preferred as a catalyst over platinum? c) Why SO3 vapours are not directly absorbed in water? Define: [2] a) Isomerism b) Catenation Name the constituents of: a) Solder b) Bronze [2] *************************************************************************
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