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Mongar Higher Secondary School Monger: Bhutan Mid-term examination -2010 Time:11/2hrs Marks:80 Sub: Chemistry Class:X Section A (Compulsory : To be attempted by all the candidates.) Question 1 Directions: Each question in this part is followed by FOUR possible choices of answer. Choose the correct answer and write it in the separate answer sheet provided. [15] i) An acid which is monobasic. a) H2SO4 b) H3PO4 c) H2SO3 d) HCl ii) a) b) c) d) The tendency of an element in a molecule to attract the electrons towards itself Electron Affinity Ionization Potential Electronegativity Valency. a) b) c) d) The crystalline substances which on exposure to air loses water of crystallization either wholly or partially are called hygroscopic substances deliquescent substances efflorescent substances desiccating agent iii) The chemical reaction given below is to be used with question iv. 2H 2 ( g ) O2 g 2H 2 O g iv) In the above reaction, the volume of hydrogen that will combine with 30 litres of oxygen to form steam is a) 60 litres b) 50 litres c) 40 litres d) 30 litres Class X Bio. Page 1 of 7 MHSS. Mid-Term Exam-2010 v) a) b) c) d) An acid which is present in the stings of ants and bees Tartaric acid Acetic acid Formic acid Oxalic acid a) b) c) d) The modern periodic law is based on Atomic weight Atomic size Atomic number Atomic radius vi) vii) a) b) c) d) A polar covalent compound H2 O2 NaCl H2O viii) a) b) c) d) Base which is used in making of soap Ca(OH)2 Mg(OH)2 NaOH NH4OH ix) a) b) c) d) When a metal atom becomes an ion it loses electrons and is oxidized it gains electrons and is reduced it gains electrons and is oxidized it loses electrons and is reduced. a) b) c) d) Compound X simply consists of molecules. The type of bonding in X will be Ionic Electrovalent Covalent Coordinate. x) Class X Bio. Page 2 of 7 MHSS. Mid-Term Exam-2010 The table given below is to be used with question X Solutions A B C D xi) a) b) c) d) xii) a) b) c) d) PH values 6 14 7 1 In the table given above, which solution has the maximum H+ ions? Solution with PH value 6 Solution with PH value 14 Solution with PH value 1 Solution with PH value 7 The chemical properties of an element depend on the electronic configuration number of valence electrons number of shells number of electrons. xiii) In what ratio will hydrogen combine with oxygen to form hydrogen chloride in the following equation H 2 Cl2 2HCl a) b) c) d) 1:1:1 1:2:1 1:1:2 2:2:1 xiv) a) b) c) d) The common name of hydrated Ferrous Sulphate is green vitriol blue vitriol white vitriol yellow vitriol xv) a) b) c) d) an atom and a cation will have the same number of protons the same number of neutrons different number of protons different number of neutrons. Class X Bio. Page 3 of 7 MHSS. Mid-Term Exam-2010 i) Match each item under column A with the most appropriate item in Column B Column A 1) Magnesium hydroxide 2) Avogadro’s number 3) Periods 4) Atomic number 5) Acetic acid Column B a) 6.023x1023 b) vertical columns c) antacid tablet. d) horizontal rows e) 6.023x1023 f) soap g) protons h) monobasic acid ii) Fill in the blanks by choosing words from the list given below. [5] ( empirical formula, salt, ionization, cation, molecular formula, base, acid, anion, dissociation, mercury, oxygen, sodium) i) A base reacts with an acid to form a …………and water only. ii) Negatively charged ion is called………. iii) ………….is a chemical formula which gives the simple whole number of different types of atoms present in a molecule of compound. iv) The metal which occurs in liquid form is……….. v) The process by which covalent compounds are converted to ions in aqueous solution is called…………. iii) Name the following [5] i) The salt formed by the complete replacement of ionisable hydrogen atoms of an acid by metal or ammonium ion. ii) The amount of substance containing particles equal to Avogadro’s number. iii) According to electronic concept, a process in which one or more electrons are lost. iv) The fundamental property used for classification of elements in the modern periodic table. v) A salt which is used in some kind of ‘iron tablets’ which people use to cure anaemia. iv) What weight of carbon dioxide is formed by the complete combustion of 6 grams of carbon in the following equation? [2] (At. Wt. ;C=12, O=16) C O2 CO2 Class X Bio. Page 4 of 7 MHSS. Mid-Term Exam-2010 v) Give at least two differences between electrovalent compounds and covalent compounds with one example each. vi) Give reasons for the following. i) Table salt (NaCl) becomes moist and sticky during rainy season. ii) Alkalis should not be left exposed to air iii) Ionic compounds are bad conductors in solid state but are good conductiors in molten state or in their aqueous solutions. iv) The atomic size decreases across the period. v) Sodium chloride solution is neutral. [3] [5] Section B (40 marks) Attempt any four questions. Question 2 a) Define the following i) Avogadro’s law ii) Basicity of acid iii) Periodicity [3] b) A part of the periodic table, sharing the position of same elements as given below. 1) 2) 3) 4) 1 2 3 Li 4 5 6C 7N 80 9 10 11Na 12 13 14 15P 16S 17 18 some of the boxes in the periodic table above contain a number a) What is this number called? [1] b) Which element should be there in the box having the number 17? [1] What is the name given to vertical columns of the periodic table? [1] Write the electronic configuration of Na [1] What is the common feature of the electronic configurations’ of the elements in the same group? [1] c) Find out the total percentage of oxygen in MgSO4.7H2O. (Mg=24, S=32, H=1, O=16) Question 3 a) Complete the following statements. i) The size of a sodium atom is………than that of chlorine atom ii) The volume occupied by 1 mole of gas at STP is…….. iii) The total number of atoms in one molecule of H2O……. iv) The only non-metal which occurs in liquid state is……. Class X Bio. Page 5 of 7 MHSS. Mid-Term Exam-2010 [2] [4] b) Calculate the number of cations and anions present in one mole of ferric chloride. (FeCl3) [2] c) i) What should be the nature of the substance applied on the stings of wasps? What types of reaction take place? [2] ii) What is the volume occupied by 8g of sulphur dioxide? [2] ( At.Wt:- S=32, O=16) Question 4 a) i) Distinguish between Acid –Base indicators and Universal indicator [2] ii) The empirical formula of a compound is C2H5. It has a vapour density of 29. Determine the relative molecular mass of the compound and hence its molecular formula. [3] b) An atom X is in second period and group II A of the periodic table. i) What is the number of valence electrons in its atom? [1] ii) What will be the formula of the compound formed by X with chlorine? iii) [1] Is it a metal or non-metal? [1] c) i) ii) Acids dissolve in water to produce positively charged ions. Draw the structure of these positive ions. [1] What type of bond is present in sodium chloride, NaCl? [1] Question 5 a) Lhatu found that the blue copper sulphate crystals when kept open in air turned white. i) What is the reason for this change? [1] ii) State the nature of salt? [1] b) i) Define the term molecular formula. ii) Chlorofluoro carbons (CFC’s) are the compounds that contain only carbon, Chlorine and fluorine. A particular CFC has the following composition. C = 8.7% , F = 13.8% , Cl= 77.5% Calculate the empirical formula of the compound. ( At.Wt= C= 12, F=19, Cl= 35.5) [3] Class X Bio. Page 6 of 7 MHSS. Mid-Term Exam-2010 c) i) ii) iii) Question 6 a) i) ii) iii) b) i) ii) State Gay-Lussac’s law. [1] What volume of oxygen would be required to burn completely 150ml of carbon monoxide? Calculate the volume of carbon dioxide formed in the reaction [2] 2CO+O2 → 2CO2 How many moles of hydrogen chloride can be produced from 1 mole of hydrogen and one mole of chlorine? [1] Define ionization potential. What happens to metallic character down the group? How many horizontal rows are there in a periodic table? [1] [1] [1] Give one difference between acid salt and normal salt with one example each. [2] Comment on the statement, “all alkalis are base but all bases are not alkalis” [1] c) i) ii) Define relative atomic mass [1] 1.55g of sodium peroxide reacts with water according to the following equation. 2Na2O2 + 2H2O→ 4NaOH + O2 Calculate 1) Weight of sodium hydroxide formed. 2) Volume of oxygen liberated at STP 3) Weight of oxygen liberated. [1] [1] [1] All the best Class X Bio. Page 7 of 7 MHSS. Mid-Term Exam-2010