Formatting page ...
GOLDCREST HIGH-LATUR ON THE WINGS OF EXCELLENCE PRELIMINARY EXAMINATION SUBJECT:- CHEMISTRY PAPER-1 (THEORY) TIME:- 3 HOURS DATE:-21.12.2017 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) --------------------------------------------------------------------------------------------------------------------All questions are compulsory Question 1 is of 20 marks having four sub parts, all of which are compulsory. Question numbers 2 to 8 carry 2 marks each, with any two questions having internal choice. Question numbers 9 to 15 carry 3 marks each, with any two questions having an internal choice. Question numbers 16 to 18 carry 5 marks each, with an internal choice. 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 brackets [ ]. 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 problems, use the following data: Gas constant R = 1.987 cal deg-1 mol-1 = 8.314 J K-1 mol-1 = 0.0821 dm3 atm K-1 mol-1 1 L atm = 1 dm3atm = 101.3 J 1 Faraday = 96500 coulombs. Avogadro s number = 6.023 x 1023 Question:-1 (a) Fill in the blanks by choosing the word /words from those given in the brackets: [4 x 1=4] (increases, decreases, 68,efficient, cubic,less than, zero,sp3d2 small, , 54,atoms, unpaired,sp3d,pentagonal bipyramidal, 74, more, d2 sp3 greater than, octahedral) (i)The Van t Hoff factor of acetic acid solution is _____than one and the value of normal colligative property is _______ than the observed colligative property of this solution. (ii) The acidic strength of phenol is_____ ethyl alcohol but_____ nitro phenol. (iii) Both ccp and hcp are _____ close packing and occupy about____ % of available space. (iv) SF6 has _____ hybridization and _____ structure (b)Complete the following statements by choosing the correct alternative from the choices given: [4 x 1=4] (i) The molal freezing point constant of water is 1.86 K Kg mol-1.Therefore, the freezing point of 0.1M NaCl solution in water is expected to be : (1)-1.86 oC (2) -0.372 oC (3) -0.186 oC (4) +0.372 oC (ii) For the first order reaction the rate constant for decomposition of N2O5 is 6 x 10-4 Sec -1.The half life period for the decomposition in seconds is: (1)11.55 (2)115.5 (3)1155 (4) 1.155 (iii)When acetaldehyde is treated with Grignard reagent, followed by hydrolysis the product formed is : (1)Primary alcohol (2) Secondary alcohol (3) Carboxylic acid (4) Tertiary alcohol (iv) In the complexs [Fe (CN)6]3- and [Pt(en)(H2O)2(NO2)(Cl)]2+ the respective oxidation numbers of central metal atoms are : (1) +3 and +4 (2) +6 and +4 (3)+6 and +3 (4) +3 and +3 Page 1 of 6
|
