Formatting page ...
Chemistry Date: 10th Jan 2019 Full Marks :80 Std X Time :2 Hrs -----------------------------------------------------Section 1 (Compulsory)-----------------------------------------------------------Question I. Choose the most appropriate answer:[10] (1) Which of the following is an orange coloured salt. (a) Calcium chloride None of the above. (2) (b) Zinc nitrate hexahydrate (c) Ammonium dichromate (d) In the extraction of Iron from Hematite if the gangue is acidic in nature then the flux added is:(a) Limestone (b) Sand (c) Iron (III) oxide (d) NaOH. (3) During the electrolysis of molten NaCl , which of the following does not occur. (a) Sodium ions are reduced to Sodium atoms (b) Chloride ions are oxidized to chlorine atoms (c) there is an evolution of yellowish green gas at the anode (d) It is an example of a Redox reaction. (4) In the lab preparation of Ethene if the temp is maintained at 140 C instead of 170 C the product formed is: (a) Dimethyl Ether (b) Ethyl acetate (c) Ethyl ethanoate (d) Ethoxy ethane. (5) The ratio between the molecules present in 1 g of Hydrogen and 32g of oxygen is (a) 1:1 (b) 2:1 (c) 1:2 (d) none of the above (6) Which of the following ores can be concentrated by the froth floatation process:(a) Calamine (b) Horn Silver (c) copper glance (d) Siderite. (7) Which of the following alloys is used to manufacture electric heaters and Rheostats. (a) German Silver (b) stainless steel (c) Duralumin (d) Alnico. (8) Which of the following reactions will evolve a colored gas: (a) Action of warm water on Aluminium Carbide (c) action of Lead dioxide on hot and conc. HCl (9) (10) Which of the following makes steel hard but not brittle:(a) Annealing (b) Tempering (c) Quenching (b) Action of Zinc on Ethanoic acid (d) Heating a mixture of Sal ammoniac and Ca(OH)2 (d) Leaching. In the lab preparation of HNO3 , sulphuric acid acts as a (a) Less volatile acid (b) Drying agent (c) Typical acid (d) both (a) and (b). -------------------------------------------------------------------------------------------------------------------------------------------------------- Question II. [5] (1) State your observations when:- Dilute HCl is added to Pb(NO3)2 and then heated. (2) (3) (4) (5) Barium chloride solution is added to sodium sulphite solution and then heated. Dilute H2SO4 is added to CuCO3 . Ethyne gas is passed through bromine dissolved in CCl4. Acetic acid is heated with Ethanol in the presence of Conc. H2SO4. --------------------------------------------------------------------------------------------------------------------------------------------Page 1 of 4 Question III. [2+3] (1) An unknown gas 'B' has a mass of 11.2 g and a volume of 40.32 L at S.T.P. Calculate its V.D. (2) What is the total volume of gaseous products formed when 10.25 g of Calcium nitrate is thermally decomposed . -------------------------------------------------------------------------------------------------------------------------------------------Question IV. Identify the term/phrase/substance in each of the following and name them:[10] (1) The type of reactions that alkenes undergo. (2) The crackling sound given out when crystalline salts are strongly heated. (3) The electron/s present in the outermost shell of any atom. (4) The tendency of an atom to attract the shared pair of electron/s in a molecule of a compound. (5) The chemical process used to separate Gangue from Ore . (6) The ability of Carbon to form compounds with straight/branched or cyclic chains of varying length. (7) Compounds with same molecular formula but different structural formula/formulae. (8) The unique property of Carbon atom due to its no. of valence electrons. (9) Thermite welding/Thermite process is also known as ___________________________________? (10) The gas /gases /vapors evolved when Ammonium nitrite is heated strongly. ---------------------------------------------------------------------------------------------------------------------------------------------------Question V. Match the salts given in Column I with their method of preparation given in column II. [5] Column I Column II 1. Lead nitrate from Lead monoxide A. Simple displacement 2. Magnesium chloride from Mg B. Titration 3. Ferric Chloride from Iron filings C. Neutralization 4. Sodium nitrate from Sodium D.Precipitation hydroxide 5. Zinc Carbonate from Zinc sulfate E. Combination -----------------------------------------------------------------------------------------------------------------------------------------------------Question VI. Re-write the following sentences by using the correct symbol >(greater than) or <(less than) in the blanks given [5] (1) The I.P value of K is _______________that of Na. (2) The elecronegativity of F is ________________that of Cl. (3) The chemical reactivity of Pb is _______________that of H. (4) The % of Al present in Alnico is _______________ that of Fe. (5) The reactivity of Ethene is _______________that of Ethane. ------------------------------------------------------------------------------------------------------------------------------------------------------- Page 2 of 4 Section II (answer any four of the six questions) Question VII Answer the questions that follow with reference to the diagram given below. [10] 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. What is prepared in the above process? Name A (liquid) B and C. Why is an all glass apparatus used? Explain why C has a particular color. How can you remove this color? Write a balanced chemical equation for the preparation of C by the above process. Why does C not evolve hydrogen gas when treated with granulated Zinc? What temperature should be maintained in the above process? What would happen if the temperature is not maintained? By which process is 'C' prepared in the industry? Question VIII. Answer the questions that follow with reference to the diagram given below. [10] 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. What is the name of the above experiment? Which property of the substance is demonstrated by the above experiment? This experiment can also be performed with another gas. Name the gas. Both the gases have a common property. (they form_________________?) fill in the blank. Write an equation for the catalytic oxidation (excess oxygen) of the gas X. The gas X acts as an oxidizing or reducing agent? give an equation to show its property. When this gas 'X' is passed through a liquid 'Y' a brown coloration/ppt. is observed. name 'Y'. What will you observe is this gas 'X' is passed through green vitriol solution? Write a balanced chemical equation for the laboratory preparation of gas X. Name the ions formed when gas 'X' is dissolved in water. -----------------------------------------------------------------------------------------------------------------------------------------Page 3 of 4 Question IX Write balanced chemical equations for the following conversions [5] 1. Zinc carbonate 2. A E Zinc Nitrate B Zinc Hydroxide C Zinc Oxide D Sodium Aluminate Write balanced chemical equations for the following conversions [5] Ethanol-----A----- Ethylene-----B---- Ethane----C--- 1,2-Dibromoethane-----D----- Ethyne--E----- Ethene -----------------------------------------------------------------------------------------------------------------------------------------Question X. Give reasons/explain the following . (list and explain all reasons, equations not required) [10] 1. 2. 3. Table salt turns sticky in the rainy season Alumunium is a self protecting metal. The electrolytic mixture is covered by a layer of coke in the Hall-Herault's process. 4 5. Pure alumina is not used for the extraction of Aluminium. There are a large no. of organic compounds. ------------------------------------------------------------------------------------------------------------------------------------------Question XI. 1. is An experiment showed that in 10.47g of Lead chloride, the mass of lead present is 6.21g. What [4] the empirical formula of lead chloride? (Pb=207 Cl=35.5)? 2. Calculate the % of Al in Cryolite. (Al=27, Cr=52, O=16, F=19, Na=23, Ca=40) [3] 3. What mass of Ca would weigh the same as 224 c.c of Helium gas [3] -------------------------------------------------------------------------------------------------------------------------------------------Question XII. 1. Distinguish between the following pairs of compounds.(In tabular form only) [2] (a) (b) Sodium sulphate and Sodium sulphite. Ferrous nitrate and Ferrous chloride. 2. 1g of hydrogen occupies 11.22 L at S.T.P and 0.678g of an unknown gas 'X' occupies 525mL at S.T.P. [4] calculate the Molecular weight of the gas 'X'. 3. 1 g of a hydrated salt of Iron contains 0.2014g of Fe, 0.1153g of Sulfur, 0.2301 g of oxygen and [4] 0.4532 g of water of crystallisation. Find the empirical formula of the compound. (Fe=56, S=32, O=16, H=1) ________________________________________________________________________________________________________ ________________________________ Page 4 of 4
|
