w w ap eP m e tr .X w om .c s er June 2003 INTERNATIONAL GCSE MARKING SCHEME MAXIMUM MARK: 40 SYLLABUS/COMPONENT: 0620/01 CHEMISTRY (Multiple Choice) Page 1 Mark Scheme IGCSE EXAMINATIONS – June 2003 Syllabus 0620 Question Number Key Question Number Key 1 2 3 4 5 C B A D A 21 22 23 24 25 B D A B D 6 7 8 9 10 C A A B C 26 27 28 29 30 B D D D B 11 12 13 14 15 B D C D
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Are Aromatic Hydrocarbons Carcinogenic Aromatic hydrocarbons or arenes are hydrocarbons characterized by alternating double and single bonds between carbons. Benzene is the most common aromatic hydrocarbon‚ but there are some non-benzene based compounds called heteroarenes‚ where a carbon is replaced by an oxygen‚ nitrogen‚ or sulfur‚ that are also aromatic compounds. Aromatic hydrocarbons exist in our daily lives regardless if we recognize them or not. Aromatic hydrocarbons are ingested or
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Chemistry Assessment Coal is a combustible rock of organic origin composed mainly of carbon (50-98%)‚ hydrogen (3-13%) and oxygen with lesser amounts of nitrogen‚ sulphur and other elements. Some water is always present‚ as are grains of inorganic matter that form an incombustible residue known as ash. In New South Wales‚ black coal is mined near the eastern and western edges of the Sydney-Gunnedah Basin where the seams are relatively close to the surface. Mining along the western edge‚ where
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Table of Contents 1. Introduction 1 2. LITERATURE REVIEW 3 2.1 BIOFUELS 3 2.2 Bio-Oil Production 3 2.2.1 Bio-Oils production by Fast Pyrolysis 4 2.2.2 Bio-Oils by Liquefaction of bio-mass 6 2.3 Vegetable oil 7 2.4 Drawback of bio oil 9 2.4.1 Hydrodeoxygenation 9 2.4.2 Catalytic cracking 10 2.5 Mechanism of Catalytic Cracking 11 2.6 Kinetic and modeling for catalytic cracking 14 3. Characterization and Analysis techniques 15 3.1 catalyst characterization methods 15 3
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concept of electrophilic aromatic substitution‚ which is a type of benzene reaction. This reaction consists usually of benzene and an electrophile. The role of the nucleophile is played by the double bond on the benzene ring. IT will react will the electrophile and this reaction will form a carbon cation intermediate. With additional reactions with a base‚ the electrophile fundamentally replaces the hydrogen of the benzene. Benzene is classified as one of the countless aromatic molecules‚ and this is
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Conformational stereoisomer of butane Butane‚ C4H10 is an alkane with four carbon atoms which are bonded to each other by single bonds. Butane can form two isomers which are n-butane and isobutane. Figure1.1(a) and 1.1(b) shows the structures of n-butane and isobutane. Alkanes usually show conformational isomerism due the presence of C-C single bonds. It is important to understand that conformational isomer can only occur in compound with single bond but not double or triple bond. This is because
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form‚ write the structure of any meso compounds below. If none would form‚ write the word “NONE” below. [pic] 3. (25 points) The following reaction produces a major alkene product. First‚ on the Newman template provided draw the conformation from which the raction will occur. Then‚ on the product alkene template provided‚ draw the product that will form from this reaction. Finally‚ indicate the stereochemical designation of the major product.
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Chlorophyll clip_image002Outline the role of photosynthesis in transforming light energy to chemical energy (including raw materials needed for this process) Photosynthesis occurs in all green plants and is the beginning of nearly all food chains therefore a source of life to all living organisms. It is the process where plants transform light energy from the sun into chemical energy. By using light energy trapped by chlorophyll (light absorbing pigment)‚ plants combine carbon dioxide and
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will depend on the functional groups present. For example heptane has boiling point of 98.4 degrees (1) and 1-hexanol has boiling point of 157 degrees. (2) The fact that heptane has lower boiling point then 1-hexanol is because heptane belongs to alkane group and only has dispersion forces since it contains non polar molecules. Dipole-dipole forces exist between neutral polar molecules but heptane is non polar. Heptane does not contain hydrogen bonding as no H atoms bond with F‚ O‚ or N. On the other
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Available online at www.sciencedirect.com South African Journal of Botany 76 (2010) 652 – 654 www.elsevier.com/locate/sajb Chemical composition of the wood and leaf oils from the “Clanwilliam Cedar” (Widdringtonia cedarbergensis J.A. Marsh): A critically endangered species G.P.P. Kamatou a ‚ A.M. Viljoen a‚⁎‚ T. Özek b ‚ K.H.C. Başer b a Department of Pharmaceutical Sciences‚ Faculty of Science‚ Tshwane University of Technology‚ Private Bag X680‚ Pretoria 0001‚ South Africa b Department
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