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Chemistry Notes Chapter 1 for Class 9

This is a discussion on Chemistry Notes Chapter 1 for Class 9 within the Courses forums, part of the IT Cafe category; Q - 1) Define chemistry? Write the name of its branches: Ans: Chemistry is the branch of science that deals ...

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    Chemistry Notes Chapter 1 for Class 9

    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 name of its branches are as follow:

    (1) Physical chemistry (2) Oranganic chemistry (3) Inoranic chemistry
    (4) Bio chemistry (5) Analytical chemistry (6) Nueclear chemistry
    (7) Polymeric chemistry (8) Enviormental chemistry (9) Applied chemistry

    The various branches of Chemistry:

    Phyical chemistry: It deals with the laws and principles governing the combination of atoms and molecules in chemical reactions.

    Organic chemisty: It is the study of hydrocarbons and their derivatives. It also deals with carbon compounds with the exception of CO2 , CO etc.

    Inorganic chemisty: It is the study of elements and their compounds generally obtained from non living organisms i.e. minerals.

    Bio chemisty: It is the study of compounds of living organism i.e. plants and animals and their metabolism in the living body.

    Analytical chemisty: It is the study of methods and tecniques involved to determine kind, quality and quaintity of various components in given substance.

    Industrail or Applied chemisty: It is the study of different chemical processes involed in the chemical industries for the manufacture of synthetic products like galss, cement, paper, soda ash, fertilizsers, medicines etc.

    Nuclear chemisty: It is the study of changes occurring in the neclei of atoms, accompanied by the emission of invisible radiations.

    Polymeric chemisty: It is the study of polymerization and the products obtainded through the process of polymerization such as plastic, synthetic fibers, papers etc.

    Enviromental chemisty: It is the study of interaction of chemical materials and their effects on the enviroment of animals and plants.

    Q - 2) What is scientific method? Define Hypothsis and Theory.

    Ans: A particular method that is used to search for facts and figures is called Scientific Method. It consists observation, hypothesis, theory and scientific laws.

    Hypothesis: It may be possible answer of the problems after observation. It is also the trail idea for accumulating more knowledge or facts.

    Theory: It is the verified result of hypothesis, which is obtained with the help of careful experimentation.

    Q - 3) What is Scientific method? Write the name of its four stages and describe them:

    Scientific Methode: 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 own skill.

    Hypothesis: It is the statement that 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 again and again and is found to fit according to facts, gave valued predictions is called Scientific law.

    Q - 4) Write down the contirbution of Muslim scientists in the field of Chemistry:

    Jabir ibne haiyan: (721 803 A.D.) He is known as the father of chemisty.
    > 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 deying clothes.

    Al Razi: (862 930 A.D.) He was physician, surgeon, philosopher & alchemist.
    > He was the first person who used opium as an ansesthesia.
    > He prepared ethyle 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 conributed in the field of mathematics, medinice, medical chemistry, philosophy and astronomy.

    Q - 5) What is scientific law?

    Scientific Law: When a theory is tasted again and again and is found to fit according to facts amd gave valued predictions is called Scientific Law.

    Q - 6) Write down the contirbutions of Modern scientists in the field of Chemistry:
    Robert Boyle: (1627 1961 A.D.) He is known as father of modern chemisty.
    > 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. Prieslly: (1733 1804 A.D.)
    > He discovered oxygen, sulphur dioxide and hydrogen chloride.
    J. J. Berzellius: (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 1867 A.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. Jhon Dalton: (1766 1844 A.D.)
    > He gave atomic mass theory.
    Mendeleeff: (1824 1907 A.D.)
    > He discovered the periodic arrangements of elements. Lavoisior: (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, cosmatics, cement, fertilizers, glass and explosives etc.
    1) It helps to discovers new metarials and elements.
    2) It matters with protection of enviroment and providing need of life.
    3) It provides pharmaceutical chemicals that enhance our health and prolong our lives.

    Q - 8) Write three significant reasons to study chemistry?

    First Reason: 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.
    Second Reason: It is an intellectual enterprise, a way of explaining our material world.
    Third Reason: It figures prominently in other field, such as in biology in the advancement of medicines and useful intellectual tool for making important decisions.
    Last edited by ahti; 22nd April 2013 at 07:15 PM.

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