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  • 1.1 Q - 1) Define chemistry? Write the name of its branches: Ans: Chemistry is the branch of science that deals with the properties, compositions and structure of matter. It also deals with principles and the laws governing the changes involved in the matter. The names of its branches are as follow: 1. Physical chemistry 2. Organic chemistry 3. Inorganic chemistry 4. Bio chemistry 5. Analytical chemistry 6. Industrial or applies chemistry 7. Nuclear chemistry 8. Polymeric chemistry 9. Environmental chemistry Describe the branches of chemistry: Physical chemistry: It deals with the laws and principles governing the combination of atoms and molecules in chemical reactions. Organic chemistry: It is the study of hydrocarbons and their derivatives. It also deals with carbon compounds with the exception of CO2, CO etc. Inorganic chemistry: It is the study of elements and their compounds generally obtained from non living organisms i.e. minerals. Biochemistry: It is the study of compounds of living organism i.e. plants, animals and their metabolism in the living body. Analytical chemistry: It is the study of methods and techniques involved to determine kind, quality and quantity of various components in given substance. Industrial or Applied chemistry: Itisthestudyofdifferentchemicalprocesses involved in the chemical industries for the manufacture of synthetic products like glass, cement, paper, soda ash, fertilizers, medicines etc. Nuclear chemistry: It is the study of changes occurring in the nuclei of atoms, accompanied by the emission of invisible radiations. Polymeric chemistry: It is the studyof polymerization and the products obtained through the process of polymerization such as plastic, synthetic fibers, papers etc. Environmental chemistry: It is the study of interaction of chemical materials and their effects on the environment of animals and plants. Q - 2) What is scientific method? Define Hypothesis and Theory. A particular methodthat is usedto searchfor facts andfigures is called Scientific Method. It consists of observation, hypothesis, theory and scientific laws. It may be possible answer of the problems after observation. It is also a trail idea for accumulating more knowledge or facts. It is the verified result of hypothesis, which is obtained with the help of careful experimentation. chemistry INTRODUCTION TO CHEMISTRY Chapter IX One

2. 2 Q - 3) What is Scientific method? Write the name of its four stages and describe them: Scientific Method: A specific method that is used to search for truth or facts. And: It is based on observation, hypothesis, theory and scientific laws. Observation: It is the basic tool for explaining a phenomenon but it may vary from person to person according to his skill. Hypothesis: The statement may be possible answer of the problems after observation. It is also the trail idea for accumulating of more knowledge or facts. Theory: It is the verified results by hypothesis, which is obtained with the help of careful experimentation. Scientific law: When a theory is tasted repeatedly and is found to fit according to facts, gave valued predictions is called Scientific law. Q - 4) Write down the contribution of Muslim scientists in the field of Chemistry: Jabir ibne Hayyan: (721 803 A.D.) He is known as the father of chemistry. He invented experimental methods for preparation of Nitric acid, Hydrochloric acid and white lead. He developed method for extraction of metal from their ores. He developed method for dyeing clothes. Al Razi: (862 930 A.D.) He was physician, surgeon, philosopher & alchemist. He was the first person who used opium as an anesthesia. He prepared ethyl alcohol by fermentation process. He divided the substances into living and non- living origins. Al Beruni: (973 1048 A.D.) He contributed in mathematics, physics, chemistry, metaphysics, geography and history. He determined the densities of different substances. Ibne Sina: (980 1037A.D.) He contributed in the field of mathematics, medicine, medical chemistry, philosophy and astronomy. Q - 5) What is scientific law? Scientific Law: When a theory is tasted repeatedly and found to fit according to facts, and gave valued predictions is called Scientific Law. 3. 3 Q - 6) Write down the contributions of Modern scientists in the field of Chemistry: Robert Boyle: (1627 1961 A.D.) He is known as father of modern chemistry. He was first to put forward the idea that chemistry should be regarded as a systematic investigation of nature promoting knowledge. He tried to purify chemicals to obtain reproducible reactions. J. Priestly: (1733 1804 A.D.) He discovered oxygen, Sulphur dioxide and hydrogen chloride. J. J. Berzelius: (1779 1848 A.D.) He introduced the idea of symbols, formulae and chemical equation to make the study more systematic. Arrhenius: (1859 1927 A.D.) and M. Faraday: (1791 1867A.D.) They both gave the Ionic theory and Laws of electrolysis. Scheele: (1742 1786 A.D.) He discovered chlorine. J. Black: (1728 1799 A.D.) He made study of carbon dioxide Cavendish: (1731 1810 A.D.) He discovered Hydrogen. John Dalton: (1766 1844 A.D.) He gave atomic mass theory. Mendeleev: (1824 1907 A.D.) He discovered the periodic arrangements of elements. Lavoisier: (1743 1794 A.D.) He discovered that oxygen constituted about one-fifth of air. Q - 7) What important role chemistry plays in the society: Ans: Chemistry plays very important role in the society to prepare such as food, synthetic fibers, plastics, medicines, soap, detergents, cosmetics, cement, fertilizers, glass etc. Q - 8) Write three significant reasons to study chemistry? It has important practical applications in the society the development of life saving drugs is one and complete list would touch upon most areas of modern technology. It is an intellectual enterprise, a way of explaining our material world. It figures prominently in other field, such as in biology in the advancement of medicines and useful intellectual tool for making important decisions 4. 4 Q - 1) Sate the following laws: It states that in any chemical reaction the initial weight of reacting substances is equal to the final weight of the products. It states that the different samples of the same compound always contain the same elements combined together in the same proportions by mass. It states that if two elements combine to form more than one compound. The masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers or simple multiple ratios. It states that the two different elements separately combine with the fixed mass of third element, the proportions shall be either in the same ratio or simple multiple of it. Q - 2) State law of conservation of mass with Landolts experiments Law of conservation of Mass: It states that in any chemical reaction the initial weight of reacting substances is equal to the final weight of the products. Landolts experiment: German Chemist H. Landolts tested different chemicals to verify Law of conservation of mass. 1. He took H shaped tube that has two limbs. 2. He filled limbs A and B with Silver Nitrate (AgNO3) & Hydrochloric acid (HCl) respectively. 3. The tube was sealed and weighted initially. 4. The reactants were mixed by inverting and shaking the tube. 5. After mixing the tube weighted again and he observed that weight, remain same. Chemical Reaction: AgNO3 + HCl AgCl + HNO3 Q - 3) State the law of Constant, Definite proportion with example? Law of Definite proportions: It states that the different samples of the same compound always contain the same elements combined together in the same proportions by mass. Example: Every sample of pure water, through prepared in laboratory or obtained from rain, river, or water pump contains one part of Hydrogen (H) and eight parts of Oxygen (O). Like H2O = 2 : 16 or 1 : 8 chemistry CHEMICAL COMBINATION Chapter IX TWO 5. 5 Q - 4) State the law of multiple proportions with example: Law of Multiple proportions: It states that if two elements combine to form more than one compound. The masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers or simple multiple ratios. Example: Carbon (C) form two stable compounds with Oxygen (O) namely carbon monoxide (CO) and carbon dioxide CO2. Compound Mass of Carbon (C) Mass of Oxygen(0) Ratio of Oxygen (0) CO 12 16 1 CO2 12 32 2 Q - 5) State the law of Reciprocal proportion with example? It states that the two different elements separately combine with the fixed mass of third element, the proportions shall be either in the same ratio or simple multiple of it. Example: When two elements Carbon (C) and Oxygen (O) separately combine with fixed mass of Hydrogen (H) to form methane CH4 and water H4O. Ratio of H is 1 in CH4 & H2O Ratio of C is 3 in CH4 & CO2 Ratio of O is 8 in H2O & CO2 H CH4 H2O 12 : 4 2 : 16 3 : 1 CO2 1 : 8 C O12 : 32 3 : 8 Q - 6) What is Einstein theory? & Write reaction B/W mass & energy: Einstein Theory: The famous physicist and mathematician Albert Einstein proposed the relation between mass and energy. i.e. There is no detectable gain or loss of mass in a chemical reaction. Mathematically E = mc2 where E is energy, m is mass and c is speed of light. Q - 7) What is chemical reaction? Define and give example each of the following: Chemical Reaction: It is a change in which the composition of substances is changed and new substances formed. It has five types as follows. (1) Decomposition Reaction: It is the reaction in that breaks down a compound or chemical substances to form two or more substances. Heat CaCO3 CaO + CO2 6. 6 (2) Addition Reaction: It is the reaction in which two or more substances combine together to form new substances. Example: CaO + CO2 CaCO3 Example: Na + Cl2 2NaCl (3) Single Displacement Reaction: It is the reaction in which one atom o

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