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SARALA BIRLA ACADEMY- BANGALORE PRE-BOARD EXAMINATIONS 2017 2018 CHEMISTRY (Two Hours) Grade X Monday, 15/01/2018 _____________________________________________________________________________________ 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 Paper is divided into two parts, Section I and Section II. Section I is compulsory. Attempt any four questions from Section II The intended marks for questions or parts of questions are given in brackets [ ] SECTION I (40 Marks) Compulsory (Answer all questions from this section) Question 1 (a) Select from the list given below (a to f), the one substance in each case which matches the description given in the parts(ii) to (vi). Copy and complete the given grid with your answer as shown for part (i). [5] (i) (ii) (iii) (iv) (v) (vi) A A. Ammonia B. Copper oxide C. Copper sulphate D. Hydrogen chloride E. Hydrogen sulphide F. Lead bromide (i) Although this compound is not a metal hydroxide, its aqueous solution is alkaline in nature. (ii) A solution of this compound is used as the electrolyte when copper is purified. (iii) When this compound is electrolysed in the molten state, lead is obtained at the cathode. (iv) This compound can be oxidized to chlorine. (v) This compound smells of rotten eggs. (vi) This compound can be reduced to copper when heated with coke. (b) Iron is extracted from its most common ore (i) ___________ . Its formula is (ii) _______. The two valencies exhibited by iron are (iii) ________ and (iv) __________. Iron , when reacts with [5] (v) _______ forms anhydrous Iron (III) chloride. ______________________________________________________________________________________ This paper consists of 6 printed pages SBA/PB/X/CHEM/2018 Turn over 1 (c) Name the following: [5] (d) Give the IUPAC names of the following: [5] (i) C2H5 O C2 H5 (ii) H C H || O (iii) CH3 C CH CH3 | (iv) H3C C CH3 | CH3 (v) H3C CH CH2 CH3 | OH (e) Answer the following: [5] (i) What is meant by group in a periodic table? (ii) State whether ionization potential increases or decreases going down a group. (iii) How many elements are there in period 2? (iv) What types of chlorides are formed by elements of group 17? (v) What property of an element is measured by electronegativity? (f) Match the following: [5] Column A Column B (i) Acid salt Sodium potassium carbonate (ii) Mixed salt Alum (iii) Complex salt Sodium carbonate (iv) Double salt Sodium zincate (v) Normal salt Sodium hydrogencarbonate ____________________________________________________________________________________ [5] SBA/PB/X/CHEM/2018 2 (i) (ii) (iii) (iv) (v) A white solid used for drying ammonia. The solution used for preparation of ethene from ethyl bromide. An alkane which is called green house gas. An alloy used in electrical fitting. A metal which gives hydrogen gas on reacting with both dilute acid and alkali. (g) Write balanced equation for the reaction of dilute hydrochloric acid with each of the following: (i) Iron (ii) Sodium hydrogen carbonate (iii) Iron(II) sulphide (iv) Sodium sulphite (v) Sodium thiosulphate solution (h) Choose the most appropriate answer: (i) Formation of chloroform from methane and chlorine is an example of A Addition B Dehydration C Substitution D Elimination (ii) Hydrogen chloride can be obtained by adding concentrated Sulphuric acid to A NaCl B Na2SO4 C Na2CO3 D NaNO3 (iii) Duralumin is an alloy of A Al and Cu B Cu and Sn C Al and Ag D Al and Fe (iv) During electrolysis of water which of the following takes place: A Oxygen is released at cathode B Oxygen is released at anode C Hydogen is released at anode D Sulphur dioxide is released at anode (v) Ammonium hydroxide will produce a reddish-brown precipitate when added to a solution of A CuSO4 B Zn(NO3)2 C FeSO4 D FeCl3 _____________________________________________________________________________ SBA/PB/X/CHEM/2018 Turn over 3 [5] [5] [5] SECTION II (40 Marks) Attempt any four questions from this Section Question 2 (a) Arrange the following as per the instruction given in the brackets: (i) Na, Cl, Mg, P (in decreasing order of atomic size) (ii) C. Li. F, N( in increasing order of electronegativity) (iii) Cl, Al, Na, S ( in increasing order of ionization potential) (iv) Li, F, C, O ( in increasing order of electron affinity) (b) State the type of Bonding in the following molecules: (i) Ammonia (ii) Magnesium chloride (c) Answer the following questions: (i) How will you distinguish between dilute hydrochloric acid and dilute sulphuric acid using lead nitrate solution? (ii) How will you distinguish between Ammonium hydroxide and Sodium hydroxide using copper sulphate solution? (d) Identify the salts P and Q from the observations given below: (i) On performing the flame test salt P produces a golden yellow flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in Ammonium hydroxide solution. (ii) When dilute HCl is added to a salt Q, a brisk effervescence is produced and the gas turns lime water milky. When NH4OH solution is added to the above mixture (after adding dil HCl), it produces a white precipitate which is soluble in excess NH4OH solution. Question 3 (a) Some properties of Sulphuric acid are listed below. Choose the role played by sulphuric acid as A, B, C or D which is responsible for the reactions (i) to (v). Some roles may be repeated. A. B. C. D. Dilute acid Dehydrating agent Non- volatile acid Oxidising agent (i) (ii) (iii) (iv) (v) CuSO4 .5H2O concH SO CuSO4 + 5H2O S + H2SO4 (conc.) 3SO2 + 2 H2O KNO3 + H2SO4 (conc.) < 200 C KHSO4 + HNO3 MgO + H2SO4 MgSO4 + H2 Zn + 2 H2SO4 (conc.) ZnSO4 + SO2 +2 H2O 2 4 [2] [2] [5] 0 SBA/PB/X/CHEM/2018 [4] [2] 4 (b) Give balanced equations for the following reactions: (i) (ii) (iii) (iv) (v) Dilute nitric acid and Calcium carbonate. Concentrated hydrochloric acid Lead (IV) oxide. Catalytic oxidation of Ammonia. Ammonium chloride and calcium hydroxide. Zinc sulphide and Dilute sulphuric acid. Question 4 (a) A compound has the following percentage composition by mass: Carbon = 54.55%, Hydrogen = 9.09% and Oxygen =36.26%. Its vapour density is 44. Find the Empirical and Molecular formula of the compound. (H=1; C=12; O= 16) (b) Give the electron dot structure of the following (i) NH3 (ii) CH4 (iii) H3 O+ (c) Compare the properties of covalent and electrovalent compounds on the basis of: (i) Solubility (ii) Structure Question 5 (a) Gas A obtained by the dehydration of Ethanol undergoes complete combustion to form its respective oxide. (i) Identify Gas A . (ii) Give balanced chemical equation for the reaction. (iii) What volume of Carbon dioxide is produced by burning 50 cm3 of ethene in air of oxygen ? (iv)Name the law applied in solving the above problem. (b) AgNO3 + NaCl AgCl + NaNO3 How many grams of Silver nitrate is required to precipitate 287 g of Silver chloride? (N-14, O-16, Cl-35.5, Ag-108) (c) If a compound has empirical formula CH2O and its molecular weight is 180, calculate its molecular formula. [5] [5] [3] [2] [5] [3] [2] Question 6 (a) (i) 0.48g of a gas forms 100cm3 of vapours at s.t.p. Calculate the gram molecular weight of the gas. (ii) Calculate the number of molecules in 1 kg of sodium chloride. ( Na-23, Cl-35.5) ____________________________________________________________________________ SBA/PB/X/CHEM/2018 Turn over 5 [4] (b) A gas cylinder can hold 1kg of hydrogen at room temperature and pressure: (i) Find the number of moles of hydrogen present. (ii) What weight of CO2 can the cylinder hold under similar conditions of temperature and pressure? (H-1, C-12, O-16) (iii) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO2 molecules in the cylinder under the same conditions of temperature and pressure. (iv) State the law that helped you to arrive at the above result. (c) Write a balanced chemical equation for the preparation of each of the salts : (i)Zinc carbonate (ii)Ammonium chloride crystals Question 7 (a) From the following organic compounds given below, choose one compound In each case which relates to the description [i] to [iv]: [Ethyne, ethanol, acetic acid, ethene, methane] (i) An unsaturated hydrocarbon used for welding purposes. (ii) An organic compound whose functional group is carboxyl. (iii) A hydrocarbon which on catalytic hydrogenation gives a saturated hydrocarbon. (iv) An organic compound used as a thermometric liquid. (b) (i) Why is pure acetic acid known as glacial acetic acid? [4] [2] [4] [3] (ii) Give a chemical equation for the reaction between ethyl alcohol and acetic acid. (c) There are three elements E, F, G with atomic numbers 19, 8 and 17 respectively (i) Classify the elements as metals and non-metals (ii) Give the molecular formula of the compound formed between E and G. State the type of chemical bond in this compound. ________________________________________________________________________________ SBA/PB/X/CHEM/2018 Last page 6 [3]
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