by : Directorate of Education‚ Delhi SOME IMPORTANT REASONING BASED QUESTIONS OF ORGANIC CHEMISTRY 1. Chlorobenzene is less reactive than chloromethane. Ans. In chlorobenzene‚ each carbon atom of benzenering is sp2 hyridised and is electron withdrawing. Chlorine atom donates a lone pair of electron and acquire positive charge. The negative charge is delocalised on ortho and para position by resonance. C-Cl bond acquires partial double bond character and is 169 pm as compared to 17.0 pm in chloromethane
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Fireworks and What Makes Them Go Sparks! Colors! Things that go BOOM! Chemistry doesn’t get much better than this. Ever notice how minutes drag on for hours when you’re waiting for a fireworks show to begin? Everyone’s thinking the same thing: The sky is dark enough the hot dogs are all eaten…come on when are they going to start? Then the first rockets streak into the sky…Ooh! Aah! Yes‚ it was worth the wait. The birthplace of fireworks is generally recognized as China.
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for the end point and the second derivative and titration curve allowed us to get the volume of the equivalence point. The key difference between the end point and the equivalence point is that the end point is just an indicator of when the color changes and titration stops. The equivalence point is when the H+ ions are neutralized by OH- ions‚ which occurs when both are used up in the reaction causing the pH to be 7. The molarity of NaOH from the indicator was exactly .500 M‚ but the molarity
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PAHANG TRIAL 2009 EXAMINATION CHEMISTRY PAPER 2 MARKING SCHEMES SECTION A - Structural Questions: Question 1. (a) (i) The presence of isotopes 1M (ii) Let the abundance of 63X be a %. The % abundance of 65X. = ( 100 – a ) 1M Relative atomic mass = ( 62.93 x a) + ( 64.93 x ( 100 -a) ) 1M
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Match and Water in a Glass Science Magic Trick Fun Trick with Fire and Water This is a simple and interesting science magic trick involving fire and water. All you need is water‚ a glass‚ a plate‚ and a couple of matches. Pour water into a plate‚ light a match in the center of the dish and cover it with a glass. The water will be drawn into the glass. Match and Water Trick Materials • plate • water • 2 wooden matches • a quarter or other large coin • colored water
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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Soft clean eraser Soft pencil (type B or HB is recommended) 0620/01 October/November 2008 45 Minutes *6400528663* READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples‚ paper clips‚ highlighters‚ glue or correction fluid. Write your name‚ Centre number and candidate number on the
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Acids And BAses Acids And BAses 8.1 8.2 8.3 8.4 18.1 18.2 18.3 18.4 18.5 Theories of acids and bases Properties of acids and bases Strong and weak acids & bases The pH scale Calculations involving acids and bases (AHL) Buffer solutions (AHL) Salt hydrolysis (AHL) Acid-base titrations (AHL) Indicators (AHL) 8 8.1 THeORies OF Acids And BAses 8.1.1 Define acids and bases according to the Brønsted–Lowry and Lewis theories. 8.1.2 Deduce whether or not a species could act as a Brønsted–Lowry
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Bibliography: Heyworth‚ Rex M Dr‚ and J G R Briggs. Chemistry Insights. Singapore: Pearson Education South East Asia‚ 2007 http://www.google.com http://www.ausetute.com.au/elecysis.html http://www.nmsea.org/Curriculhttp://www.nmsea.org/Curriculum/7_12/electrolysis/electrolysis.htmum/7_12/electrolysis/electrolysis
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Discuss the use of technology in investigating one cognitive process-Alzheimer’s disease and memory loss Alzheimer’s disease is a degenerative brain disorder that results in memory loss‚ impaired thinking and personality change. No blood test‚ brain scan‚ physical exam can definitely diagnose Alzheimer’s disease. PET scan detect radioactively tagged glucose that are injected into a patient’s body before the imaging. Glucose enters through blood stream and brain. The most active brain areas
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CHEMISTRY OF NICOTINE Date Submitted: March 17‚ 2010 Introduction Tobacco has a long history and has had a significant impact since first introduced to Western society in the 16th century. There is evidence that Native Americans were using tobacco long before the 16th century. They smoked through a pipe for special religious and medical purposes but the worldwide spread of tobacco was initiated as a result of European discovery by Spanish‚ Portuguese and French explorers.(1‚2) Christopher
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