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STD X DATE 03/02/2018 SMT. SULOCHANADEVI SINGHANIA SCHOOL SUB EXAM TIME MARKS CHEMISTRY PRELIM set C 2hrs 80 General Instructions i. This question paper is divided into two sections. ii. Section-I is compulsory. iii. Attempt any four questions in section-II. iv. The intended marks for questions or parts of questions are given in brackets []. SECTION I ( 40 Marks) (Attempt all questions) Q1. (a) For parts (i) (x) select the correct answer from choices A, B, C, D which are given. Write down only the letter corresponding to the correct answer. [5] (i) The metal oxide which can react with acid as well as alkali is A. Silver oxide B. Copper(II) oxide C. Aluminium oxide D. Calcium oxide (ii) Which of the following is not a common characteristics of a covalent compound? A. Low melting point B. Does not conduct electricity C. Consists of ions D. Insoluble in water (iii) The organic compound formed by the reaction of ethanoic acid with methyl alcohol is A. Methyl acetate B. Ethyl methanoate C. Ethyl acetate D. Ethyl formate (iv) Iron (II) sulphide is prepared in laboratory by A. Neutralization B. Precipitation C. Synthesis D. Direct combination (v) The volume occupied by 15 g of ethane at STP is (H = 1, C = 12) A. 5.6 dm3 B. 22.4 dm3 C. 11.2 dm3 D. 44.8 dm3 (b)Identify the anion from underlined word. [5] i) Salt solution with Barium chloride gives a white precipitate. ii) Salt & conc Sulphuric acid reacts to give a gas which fumes in moist air iii) Black salt reacts with conc Hydrochloric acid to give a greenish yellow colour gas iv) Salt on heating gives reddish brown colour gas v) Salt reacting with dilute acid gives a gas which turns acidified potassium dichromate solution green (c) Name the following: [5] (i) The most electronegative metal. (ii) The gas that burns in oxygen with a green flame. (iii) The substance which reacts with water to produce acetylene. (iv)The gas liberated when an active metal is reacted with hydrochloric acid. (v) A colourless gas which burns with a pale blue flame, forming carbon dioxide. (d) What will you observe when (i) Concentrated nitric acid is poured over saw dust. (ii) Sodium hydroxide is slowly added to Iron (III) chloride solution. (iii) Lead carbonate is heated and then cooled. (iv) Ammonia is passed over heated lead oxide. (v)Silver nitrate is heated (e) Match the following compounds with their uses given: Compounds 1. Oxalic acid 2. Ethanol 3. Butane 4. Ethyne 5. Citric acid 6. Ethene [5] [6] Uses (a) Production of oxyacetylene flame (b) Manufacture of polymers (c) Components of fruit juice (d) Important component of LPG (e) Removing of ink stains (f) Thermometric liquid (e) (i)How many atoms of carbon has a young man given his bride to be if the engagement ring contains 0.50 caarat diamond? There are 200 mg in a carat. [5.02 x !0 23 atoms] (ii) Element X is a metal with valency 1. Element Y is a non metal with a valency 2. 1. Write equations to show how X and Y form ions. 2.Write the formula of the compound formed between X and Y. [4] (f ) Name the terms defined as follows: [6] i. The amount of energy absorbed or required to remove one or more electrons from the valency shell of an isolated gaseous atom. ii. The tendency of an atom to attract electrons to itself when combined in a compound. iii. A hydrocarbon with double or triple bond. iv. A salt in which the hydrogen of an acid has been wholly replaced by a metal. v. The process of concentration of ore based on preferential wetting of ores. (g) Answer the following questions related to electroplating of copper wire with silver metal. [4] i. The ions present the electrolyte are ___________ ii. Cell reaction: Cathode: __________________ Anode: __________________ iii. The two precautions taken during electroplating are:___________ iv. Draw neat diagram of above set up. SECTION II ( 40 Marks) (Attempt any four questions from this section) Q.2.(a) Give reasons for the following: [2] (i) In the laboratory preparation of nitric acid, the mixture of concentrated sulphuric acid and sodium nitrate should not be heated very strongly above 200 C. (ii)Commercial nitric acid is yellow in colour but when diluted with water, it turns colourless. (b) Write balanced chemical equations for the following conversions: (i) Methane reacts with chlorine in the presence of diffused sunlight. (ii) Silver nitrate to diamine silver chloride. (iii) Nescent chlorine is prepared from Conc Nitic Acid (iv) Acetylene converted to ethane [5] (c) Atoms of two elements X and Y have electronic configuration (2, 8, 18, 2) and (2, 8, 7) respectively. Answer the following questions: [3] (i). To which periods and group of the periodic table do X and Y belong? (ii) Amongst X and Y which forms covalent bond with hydrogen? Draw the electron dot structure of the compound formed. Q.3.(a) (i) What is formula of Brown ring? [3] (ii) State which solution has to be freshly prepared for brown ring?. (iii) Which anion is tested ? (b)(i) Explain why halogens have very strong electron affinity? [4] (ii)Draw the electron-dot structure of Hydroxyl ion . (iii) Concentrated solution of acetic acid is a weak acid as compared to dilute solution of HCl.Why? Explain your answer. (iv) What is glacial acetic acid? Why is it known so? (c) Potassium nitrate on strong heating decomposes as under: [2] 2KNO3 2KNO2 + O2 Calculate i. Weight of KNO2 formed. ii. Weight of O2 formed when 5.05g of KNO3 decomposes completely (K = 39, O = 16 , N = 14 ) (d) Draw the structures of the following compounds: i. Pentan-2-ol ii. 1,2- dichloroethane [1] Q.4 (a) [4] (i) In construction work alloy duralumin is used instead of pure aluminium. Explain, why? (ii) With reference to the reduction of copper oxide, iron(II)oxide, lead (II) oxide and magnesium oxide by hydrogen, place the oxides in order of increasing ease of reduction. (iii)Name an alloy of : 1. Lead used in electrical work in joining metals. 2. Copper in electrical appliances or household vessels. (b) Complete and balance the following chemical equations : [6] 200C i. C2 H4 + B C2H6 Ni alk. KMnO4 ii.CH2=CH2 iii. A + H2SO4(conc.) iv. S + HNO3 Br2 + ___ + ___ v. KMnO4 + H2SO4+H2S vi C + H2SO4 (conc) Q.5. (a) i. How do alcohols differ structurally from alkanes? Describe the basic steps involved in the preparation of ethanol from sugar. [2] [4] (b) Sulphur Sulphuric acid B D Sulphur C Sulphur dioxide trioxide E F Sodium sulphite Refer to the flow sheet diagram and answer the following? [4] i. Name the catalyst which helps in the conversion of sulphur dioxide to sulphur trioxide in step C. ii. In the Contact process for the manufacture of sulphuric acid, sulphur trioxide is not converted to sulphuric acid by reacting it with water. Instead a two steps procedure is used. Write equation for the two steps involved in D. iii. What type of substance will liberate sulphur dioxide from sodium sulphite in step F? iv. Write the equation for the reaction by which sulphur dioxide is converted to sodium sulphite in step E? Q.6. (a) [5] Chemical Reagent compounds/Ions Ammonia Nessler s reagent Sodium Carbonate solution Sulphur dioxide Ammonium hydroxide Acetylene Observation Brisk effervescence Purple to colourless Gelatinous white precipitate Ammoniacal Cuprous Chloride (b) A compound on analysis gave the following percentage composition : Na= 14.31 ; S = 9.97 ; H = 6.22 ; O = 69.5 [5] Calculate the molecular formula of the compound on the assumption that all the hydrogen in the compound is present in combination with oxygen as water of crystallization. The molecular mass of compound is 322. [ At. Mass: Na = 23, S = 32, H = 1, O = 16] Q.7. (a) Iron can be made into stainless steel. (i) Give one use of stainless steel. (ii) State one advantage of stainless steel over iron. (iii) Name an element, other than iron, that is present in stainless steel. [3] (b) By observing the reactions of metals with water and dilute sulphuric acid, it is possible to put metals in order of their reactivity. [3] A, B, C and D represent four metals. Metal A B C D Reaction with water No reaction No reaction Little or No reaction Vigorous reaction Reaction with dil. H2SO4 Reacts slowly at first No reaction Reacts quickly Violent-dangerous reaction (i)Arrange metals A, B, C, D in order of their reactivity with the most reactive first. (ii) The metals used were copper, magnesium, sodium and zinc. Use information in the table to identify which of these metals was A, B, C and D. (iii) Give balanced chemical equation for the reaction of C with dilute sulphuric acid. (c) Give balanced equations for the preparation of the following salts: [4] (i) FeSO4. 7H2O (ii) ZnS (iii) PbCl2 from PbO{ 2 steps} Also name the method used .. Other important questions 1: Metallurgy chapter: Learn properties of metals eg: reaction with water, dilute acid. 2: Learn Aluminum extraction thoroughly well. Baeyers process & Hall Haraults process. 3 :all alloys with composition & uses. 4: Outcome of industrial process 5: Diagram of funnel arrangement in formation of Hydrochloric acid 6: Dot diagram of NaCl, CaO,MgO All the best
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