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STX IX CHEMISTRY DON BOSCO ACADEMY, PATNA 1ST TERM EXAMINATION 2020-2021 DATE:17.09.2020 F.M. 50. TIME: 1 HR. 30 MIN Students must write their NAME, ROLL NO and PAGE NO on every page of the answer script. SECTION I [40 MARKS] Attempt all questions from this section. Question-1. (a) Fill in the blanks from the choices given in brackets. [8] i) An atom with an electronic configuration 2, 7 and mass number 19 will have ----- neutrons ( 8/10/12) ii) Radicals carrying positive or negative charge are termed ----- (ions/atoms). iii) A chemical reaction which proceeds with the evolution of heat energy is called an ----------- reaction (endothermic, exothermic) iv) Water dissolves many substances therefore it is called an ----(solution/universal solvent.) v) Nitrogen molecule contains a ------------ bond (double, triple) vi) Ionic compounds are -------- conductor of electricity in the aqueous or molten state (good; bad) vii) The scale of temperature with -273oC as zero is called ------(Celsius scale, Kelvin Scale). viii) 2 Na (s) + 2H2O (2) ----- - - - - + H2(g) (Na2O/2NaOH) b) State the valency and formula of the radicals or ions. i) Nitrite, (ii)Sulphate, (iii) thiosulphate (iv) bicarbonate. c) i) ii) iii) iv) v) vi) vii) viii) Name the following: [8] The combining capacity of an element. The shorthand notation to represent the name of the compound. An element having valency zero . The number of protons present in the nucleus of an atom. The reaction between an acid and base to form salt and water. A nitrates which produces a brown gas on heating. The valency of an element whose electronic configuration is 2,8,2. The fixed amount of water that is associated with some compounds which is an integral part of their crystalline structure. d) i) Calculate the molecular masses of the following compounds. [4] Pb(NO3)2 (ii) C12H22O11 (iii) K2Cr2O7 (iv) CuSO4.SH2O. [Atomic masses - K = 39, Cr=52; O=16; Pb=20 7 N = 14; C = 12; S = 32; Cu = 63.5 , H = 1 ] e) Calculate the percentage composition of the following: [6] i) Nitrogen in ammonium nitrate (NH4NO3) ii) Calcium in calcium carbonate (CaCO3). [Atomic mass = Ca = 40, C = 12; O =16; N = 14; H = 1 ] f) Match the following: Column I i) Anhydrous salt ii) Deliquescent substance iii) Chemically pure water iv) Drying agent v) Efflorescent substance g) a) b) c) d) e) Column II Distilled water. Sodium chloride Ferric chloride Washing soda. Fused calcium chloride. Choose the correct answer from the options given below: i) Number of valence electrons in cl-ion are (a) 16 (b) 8 (c) 17 (d) 18. [4] [5] [5]
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