Surname Centre No. Initial(s) Signature Candidate No. Paper Reference(s) 4335/1F Examiner’s use only London Examinations IGCSE Team Leader’s use only Chemistry Paper 1F Foundation Tier Monday 9 May 2005 – Morning Time: 1 hour 30 minutes Materials required for examination Nil Items included with question papers Nil Question Leave Number Blank 1 2 3 4 5 6 7 8 9 Instructions to Candidates In the boxes above‚ write your centre number and candidate
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Micro-organisms Micro-organisms Micro-organisms (or microbes) are literally microscopic organisms‚ which can only be seen properly with the aid of a microscope. These include bacteria‚ microscopic fungi (moulds) and protoctists. Although viruses‚ which are even smaller than bacteria‚ are generally considered to be non- living entities‚ they might also be included here as they are important disease-causing agents. Micro-organisms are the most numerous organisms in any ecosystem. There are about 159
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ammonia and finally he was nominated for Nobel Prize in 1918. A significant proportion of scientists differed against granting him the Nobel Prize and they alleged him as a war criminal of WW1 because of his invention of the chemical weapon from nitrate‚ a flammable substance used to make explosives. Nevertheless‚ he was awarded the Nobel Prize in 1919. His invention of chemical weapon‚ chlorine gas‚ helped Germany to kill around 15‚000 in the battle of Ypres in 1915. In addition‚ he was also well
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E-Commerce Risks and threats Dear Buyer/Broker/Trader‚ We know how difficult it is to be successful in a campaign against Time wasting and Fraudster Commodity Sellers‚ of which the internet is full. We have created our service company to fight such dangerous organizations because too many brokers‚ with family and children to feed‚ waste several months (some even years) chasing just Fake sellers and never understand the risk involved in being an accessory to a fraud. Please‚ consider how
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Separation and Qualitative Determination of Cations and Anions Instructor’s Guide Master Materials List (complete for 24 students working in pairs) Silver nitrate‚ AgNO3‚ 0.2 M‚ 100 mL* Silver nitrate‚ AgNO3‚ 0.1 M‚ 100 mL* Cupric nitrate‚ Cu(No3)2‚ .02 M‚ 100 mL* Zinc nitrate‚ Zn(NO3)2‚ 0.2 M‚ 100 mL* Ferric nitrate‚ Zn(NO3)2‚ 0.2 M‚ 100 mL* Hydrochloric acid‚ HCl‚ 6 M‚ 125 mL* Nitric acid‚ HNO3‚ 6 M‚ 125 mL* Ammonia‚ NH3‚ 6 M‚ 125 mL* Sulfuric acid‚ H2SO4‚ 6 M‚ 125 mL* Acetic acid
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Name: __________________________________ ( ) Class: 4Q HWA CHONG INSTITUTION PRELIMINARY EXAMINATION 2010 CHEMISTRY 5072 Paper 1 Time: 1 hour INSTRUCTIONS TO CANDIDATES Do not turn the pages over until you are told to do so. Write your name and index number on the answer sheet in the spaces provided. There are forty questions on this paper. Attempt all questions. For each question‚ there are four possible answers labelled A‚ B‚ C and D. Choose the one you consider correct and
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Abstract— The present work is about preparation and characterization of high temperature oxygen sensing composite material consisting of Gadolinium doped Ceria (GDC) together with a relatively low temperature melting‚ ionic conducting glass to facilitate lower sintering and operating temperature. This paper reports the physical and ionic conductivity properties of this sintered composite as a function of operating temperature. Keywords—Gadolinium doped Ceria‚ oxygen sensor‚ composite‚ glass‚ ionic
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1. Disposing of Waste - Teachers should be aware of the appropriate method of disposal for any chemical used in the school laboratory. When in doubt‚ refer to the MSDS‚ a disposal manual‚ or the source of the chemical. a. Classification of Hazardous Waste The Environmental Protection Agency classifies wastes as: Ignitable: has a flash point below 140°C‚ is an oxidizer‚ or is an ignitable compressed gas. Corrosive: has a pH equal to or below 2.0 or a pH equal to or greater than 12.5. Reactive:
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Test #2 ANSWERS CHM 101 Part I Multiple Choice (2 points each) 1. Which element is most likely to form three covalent bonds? A) C B) Si C) P D) S E) Se 2. A chemical bond formed when two atoms share two pairs of electrons is a ________ bond; it is best described as ________. A) double; covalent B) double; ionic C) single; covalent D) single; ionic E) triple; covalent 3. Which property could describe a covalent compound? A) It conducts electricity when melted. B) Has a low boiling
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Ecology Pyramids 1. a. Sunlight b. 3190000kcal per square meter per year 2. 3. a. .8% b. Photosynthesis 4. By eating the organisms in the previous level 5. 400o0 kcal 6. 7. 8. 90% of energy is lost as heat as it is transferred through trophic levels 9. .6% 10. .09% 11. Only a tiny fraction of the original energy remains. The biomass would have to increase substantially if this system were to support another trophic level beyond the hawk 12. Since little energy is available for a single
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