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The Indian Public School, Dehradun First Pre-Board Examination- 2019-20 Chemistry / Class XII-Science/ /04.12.2019 SET-A MM: 70 Time: 3:15 Hr General Instructions: KSB - 25 (a) All questions are compulsory. (b) Section A: Q.no. 1 to 20 are very short answer questions (objective type) and carry 1 mark each. (c) Section B: Q.no. 21 to 27 are short answer questions and carry 2 marks each. (d) Section C: Q.no. 28 to 34 are long answer questions and carry 3 marks each. (e) Section D: Q.no. 35 to 37 are also long answer questions and carry 5 marks each. (f) There is no overall choice. However, an internal choice has been provided in two questions of two marks, two questions of three marks and all the three questions of five marks weightage. You must attempt only one of the choices in such questions. (g) Use log tables if necessary, use of calculators is not allowed SECTION - A Read the given passage and answer the questions 1 to 3 that follow: A graph between x/m and the pressure P of the gas at constant temperature is called adsorption isotherm. Where x is the number of mole of the adsorbate and m is the mass of the adsorbent, Adsorption isotherm of different shapes have been experimentally observed. According to the Frundlich adsorption isotherm. x/m= kp1/n where k and n are constant parameter depending open the nature of the solid and the gas. Q1. In the given isotherm select the incorrect statement: (a) x/m p1/n along OA (b) x/m p0 When point B is reached (c) x/m does not increase as rapidly with pressure along BC due to less surface area available for adsorption. (d) Nature of isotherm is different for two gases for same adsorbent Q2. Adsorption isotherm for log(x/m) and log p was found of the type This is true when: (a) P=0 (b) p=1 (c) 1/n=1 (d) p<1
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