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GOLDCREST HIGH-LATUR ON THE WINGS OF EXCELLENCE PRELIM-02 SUBJECT:-CHEMISTRY (PAPER-01) TIME:3 HOURS DATE:-19.01.17 GRADE: XII MARKS:70 General Instructions (Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time) --------------------------------------------------------------------------------------------------------------------Answer all questions in Part I and six questions from Part II, choosing two questions from Section A, two from Section B and two from Section C. All working, including rough work, should be done on the same sheet as, and adjacent to the rest of the answer. The intended marks for questions or parts of questions are given in [ ] Balanced equations must be given wherever possible and diagrams where they are helpful. When solving numerical problems, all essential working must be shown. In working out the problems, use the following Gas constant R = 1.987 cal deg mol- = 8.314 J K- mol= 0.0821 L atm K- mol- 1 L atm = 1dm atm = 101.3J Avogadro s number = 6.023 x 10 -1 1 1 1 1 3 1 23 PART- I (20Marks) (Answer all questions) Question-01 (a)Fill in the blanks by choosing the appropriate word/words from those given in the brackets: (acetaldehyde, salt solution ,0.68, R,formaldehyde,buffer solution ,0.524,i, calcium formate ,50 minutes,below,45 minutes,0.74,vant t hoff factor,Raoult s Law,weak,strong,increases,decreases,positive negative,above) [5] (i) The solution obtained by mixing appropriate amount of ------------ base and its salt with strong acid is called-------(ii) An aqueous solution of glucose boils ----------100 oC and freezes-----------0 oC . (iii) The ratio of the observed value of a colligative property to the normal value of the same property is termed as -----and is represented by letter ---------(iv) When a mixture of calcium acetate and ---------is subjected to dry distillation----------is obtained. (v) A ------- catalyst increases the rate of chemical reaction while a negative catalyst ----------- the rate of reaction. (b)Complete the following statements by selecting the correct alternatives from the choices given: [5] (i)A saturated solution of Ag2CrO4 is 2 x 10-4 moles/litre.Its solubility is: (1)4.4 x 10-8 (2)3.2 x 10 -11 (3) 2.8 x10-9 (4) 5.6 x 10 -12 (ii)A molecule contains atoms X and Y so that X occurs at the corners of the cube while Y at the face centres.The formula of the molecule can be (1) XY3 (2) XY (3) X 2Y (4)XY2 (iii) 15 moles of H2 and 5.2 moles of I2 are mixed and allowed to attain equilibrium at 500 oC. At equilibrium the concentration of HI is found to be 10 moles. The equilibrium constant for the formation HI is (1) 50 (2) 15 (3) 100 (4) 25
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