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DE ELHI PU UBLIC SC CHOOL NEWTOW N WN KOLK KATA SESSION 2013-201 14 CTION EXAMINA E ATION SELEC SS: X, SET T-A CLAS SUBJE ECT: CH HEMISTR RY LLMARK KS: 80 FUL TIME: 2 hrs. Answers s to this pap per must be e written on the paper provided p sep eparately. Yo ou will not be b allowed to write dur ring the firs st 15 minut tes. This time is i to be spen nt in readin ng the Ques stion Paper. . Thi is time given n at the hea ad of this pa aper is the time t allowe ed for writin ng the answ wers. This question paper cons sists of 5 pa ages Section I is a comp pulsory. Att tempt any four fo questio ons from Se ection II. The inte ended mark ks for quest tions or par rts of questi ions are giv ven in [ ] SECTION I (40 Marks) Attem mpt all que estions fro om this Se ection Questio on 1: A: Fill in the blan nks from th he choices given g below w: [5] a ) Salts of re epresentativ ve element ts are gener rally _____ ______ .(Co olourless/br right coloured) b) A covalent t bond betw ween two dissimilar d atoms is call led a _____ _____ coval lent bond. (Pol lar/ non-po olar) c) Generally an ionic co ompound undergoes _________ _ c chemical re eaction tha an covalent co ompounds. (Fast/slow w) d) An electro onegativity is an abilit ty of an ato om to attrac ct ________ __of electro ons towards it tself. ( Shar red pair/ lo one pair) l gas is app plied on a moist m litmus s paper it will w _____ red litmus s to e) When HCl blue.(Turn n/not turn) ) B: A group of ele ements in th he periodic c table are given g below w (Beryllium is the fir rst membe er of the group and Ba arium is th he last.) [5] Berylli ium, Magn nesium, Cal lcium, Stro ontium, Bar rium. a) Which W elem ment has th he least met tallic chara acter ? b) Which W elem ment is exp pected to ha ave the low west electro negativity? ? c) The atomic c number of o the magn nesium is 12. Write th he chemical l formula of o the compound formed wh hen magnesium reacts with phos sphate ion. . d) How many y electrons are present in the out ter shell of Barium. e) Will W the ele ements in the t group to the left of the beryll lium group p be more metallic m or less met tallic in cha aracter ? Ju ustify your answer. C: Give e suitable chemical c te erms for the e following g: [5] a) Which W forc ce of attrac ction involv ves in ionic compound d. b) Name N the charged c pa articles whi ich attract one o anothe er to form electrovale ent compounds. 1 c) A bond formed by the shared pair electrons with both electrons coming from the same atoms. d) An agent which removes moisture from other substance. e) An acid formed by heating common salt with conc. Sulphuric acid. D: Identify the gas evolved in the following reaction when: a) Potassium Permanganate is treated with conc. Hydrochloric acid. b) Calcium bicarbonate treated with conc. Hydrochloric acid. c) Action of warm water on magnesium nitride. d) Action of dil. Nitric acid on Copper sulphate. e) Action of conc. Sulphuric acid on Ethanol. E: Write down the balanced chemical equation for each of the following: a) Copper sulphite treated with dil. Nitric acid. b) Copper carbonate treated with dil. Nitric acid. c) Lead nitrate react with sodium hydroxide. d) Heating of zinc sulphide in excess of air ( oxygen ). e) Heating of Manganese dioxide reacts with aluminium. F: Match the properties and uses of alloys in List I with appropriate answer from List II 1. 2. 3. 4. 5. LIST I The alloy contains Cu and Zn, is hard, silvery and used in decorative articles. It is stronger than aluminium, light and used in making light tools. It is lustrous, hard, corrosion resistant and used in surgical instrument. Tin lowers the melting point of the alloy used in soldering purpose. The alloy is hard, brittle, takes up the polish and is used for making statue. [5] [5] LIST II a. Duralumin b. Brass c. Bronze d. Stainless steel e. Solder G: Choose the most appropriate answer from the following: a) Which of the following is not a dibasic acid? I) H2SO4 II) (COOH)2 III) HCOOH IV) H3PO3 b) Colour of precipitate formed on adding NaOH solution to iron(II) sulphate is I) White II) Green III) Brown IV) Yellow 2 [5] [5] c) HCl gas is dried by passing it through I) CaO II) P2O5 III) CaCl2 IV) Conc. H2SO4 d) With excess of chlorine, ammonia forms I) NCl3 II) HCl III) NH4Cl IV) N2 e) Oxidation of metals by HNO3 does not depends upon I) Nature of metal II) Conc. of HNO3 III) Temperature IV) Catalyst H: Saturated copper sulphate solution is electrolysed with copper electrodes. [5] a) At which electrode ( anode or cathode) are copper ions discharged ? b) When copper ions are discharged at the electrode named by you, what happens at the same time on the other electrode ? c) One electrode gains in mass. The gain in mass is (less than/ same as / more than) the loss of mass at the other electrode. Choose the correct phrase from those in bracket. d) What happens to the colour of copper sulphate solution during electrolysis ? e) What is the practical value of this particular electrolysis ? SECTION II (40 Marks) Attempt any four questions from this Section Question 2: a) Give the structural formula for each of the following: I) 2,2-Dimethylbutanal II) 3-Chloropropanoic acid III) 2-Methylbut-2-ene b) Write the IUPAC name for each of the following : I) H3C C CH3 [3] [2] O II) H3C CH2 CH CH3 OH c) Write down the chemical equation for the action of: I) Aqueous KOH on ethylbromide. II) Conc. sulphuric acid on ethanol. III) Ethanoic acid on ethanol 3 [5] IV) V) Alkaline potassium permanganate on ethane. Acetic acid on magnesium. Question 3: a) Give reasons for the following: [5] I) Magnesium placed above than aluminium in activity series. II) Alkali metals are strong reducing agents. III) Oxides of highly active metals cannot be reduced by C or CO or H2. IV) Anode electrode has got to be replaced from time to time in electrolyte reduction of fused alumina in Hall-Heroult s process. V) Use of cryolite and fluorspar in the electrolyte reduction of alumina in Hall s process. b) Why silver cannot be used to prepare hydrogen from dil. Sulphuric acid. [2] c) Why the bauxite which is an ore of aluminium cannot be concentrated by froth floatation or gravity separation method? [2] d) What is smelting? Give an example. [1] Question 4: a) Give reasons for the following : I) Can we store zinc sulphate in copper vessel ? A solution of glucose does not conduct electricity. II) III) Electrolysis is a redox reaction. IV) HCl gas does not conduct electricity while aqueous HCl conducts. [4] b) What do you mean by preferential or selective discharge of ions at electrodes? What are the factors affecting it? [3] c) Electrons are getting added to an element Y. I) Is Y getting oxidised or reduced? II) What charge will Y have after the addition of electrons? III) What charge will Y migrate to, during the process of electrolysis? [3] Question 5: a) Calcium dihydrogen phosphate [Ca(H2PO4)2] is a phosphatic fertilizer. Calculate the amount of phosphorous provided to the soil, when 70.20 kg of it is spread in a field. [3] [ Ca=40, H=1, P=31, O=16 ] b) 50 cm3 of oxygen contains N molecules. How many molecules of sulphur dioxide are contained in 300 cm3, assuming all measurements are made at the same temperature and pressure? [2] c) 0.29 g of a hydrocarbon are burnt completely in oxygen. On cooling , 448 cm 3 carbon dioxide is collected at STP. From the above data calculate : I) Weight of carbon dioxide formed. II) Weight of element carbon in the carbon dioxide. III) Weight of hydrogen in the hydrocarbon. 4 of [1] [1] [1] IV) Empirical formula of the hydrocarbon. [2] Question 6: a) Salts A,B,C,D and E undergo reactions (I) to (V) respectively. Identify the anion/s present in these salts on the basis of these reactions. Tabulate your answers in the format given below. [5] I) When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric acid, is formed. II) Addition of dilute hydrochloric acid to B produces a gas which turns lead acetate paper black. III) When a freshly prepared solution of ferrous sulphate is added to a solution C and conc. Sulphuric acid is gently poured from the side of the test tube, a brown ring is formed. IV) When dilute Sulphuric acid is added to D a gas is produced which turns acidified Potassium dichromate solution orange to green. V) Addition of dilute Hydrochloric acid to E produces an effervescence. The gas produced turns lime water milky but does not affect acidified potassium dichromate solution. Salt A B C D E Anion b) Give one chemical test to distinguish between the following pairs of compound.[3] I) Zinc sulphate solution and Zinc chloride solution. II) Iron (II) chloride solution and Iron (III) chloride. III) Calcium nitrate and Calcium chloride. c) Give chemical equation for : I) The laboratory preparation of methane from sodium acetate. II) The reaction of one mole ethane from one mole of chlorine gas. [2] Question 7: a) A compound has O= 61.32% , S= 11.15% , H= 4.88% and Zn= 22.65%. The relative molecular mass of the compound is 287 a.m.u. Find the molecular formula of the compound, assuming that all the hydrogen is present as water of crystallisation. [3] b) Differentiate between roasting and calcination with an example. [3] c) What do you mean by spectator ion in the solution ? [1] d) Here is an electrode reaction : [2] 2+ Cu Cu + 2e At which electrode (anode or cathod ) would such reaction takes place ? Is this an example of oxidation or reduction ? e) Why is fused Calcium chloride used in the preparation of FeCl3. [1] 5 6
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