Knowledge of Science

                     Alcohols Hydrocarbons are the parents of other organic compounds. When One or more hydrogen atoms are replaced by the different types of atoms or group of atoms from hydrocarbons then different types of organic compounds are formed .            When hydrogen atoms are replaced from saturated aliphatic hydrocarbons by the hydroxyl group (-OH) ,then Alcohols are formed.   For example-                 -H   R-H ------------->    R-OH                                +OH Where R is the alkAl group.                    -H  CH3-H ------------->     CH3-OH                         +OH              (Methanol) So, Hydroxy derivatives of the aliphatic hydrocarbons are known as Alcohols. Classification of Alcohols- Hydroxy derivatives of the aliphatic hydrocarbons are known as Alcohols. The general formula of the alcohols are R-OH. Where R is the Alkyl group. Alcohols are classified on the basis of the number of the Hydroxyl groups (-OH) attached to

Nomenclature of Haloalkanes The name of the haloalkanes are given by two different ways- (1)Trivial or common system- In this system haloalkanes are known as Alkyl halide.        There nomenclature are performed by the adding halide word in the given alkyl group. In this system the name of the compound is written in the two different words.    For example-     CH3-Cl          (Methyl chloride) CH3-CH2-Br     (ethyl bromide)                     Prifixes of the different types of alkyl group- (a) prefix- n The means of prefix-n is normal. This is used in the straight chain of the Alkyl group.  For example-  CH3-CH2-CH2-Br                          (n-propyl bromide) (b) prefix- iso Prefix-iso is used for those Alkyl group in which methyl (--CH3) branch is present in the last of the chain. For example- CH3-CH-Br          |          CH3   (Isopropyl bromide) (c) prefix- neo Prefix-neo is used for those Alkyl group in which two methyl (--CH3) gro

      Haloalkanes and Haloarenes Haloalkanes-  The word Haloalkane is made up by the two words, -          Halo = halogen          Alkane= Aliphatic hydrocarbon (containing single bond only) So, Haloalkanes are those compounds which is formed when a hydrogen atom replaced by any halogen atom from the alkanes.                - H    R-H  -------------->      R-X                 +X Where ,   R  =  Alkyl group               X  = Halogen ( F,Cl, Br, I) For example-                                  - H          CH3-H  --------------> CH3-Cl                            +Cl Haloarenes-  The word Haloarene is made up by the two words, -          Halo = halogen    Arene= Aromatic hydrocarbon So, Haloarenes are those compounds which is formed when a hydrogen atom replaced by any halogen atom from the arenes.                - H    Ar-H  -------------->      Ar-X                 +X Where ,  Ar  =  Aromatic hydrocarbon               X  = Halogen ( F,Cl, Br,

  Allotropes of carbon  The various physical forms in which an element can exist are called allotropes of the element. The carbon elements exists in three solid forms called allotropes. The three allotropes of the carbon are - (1) Diamond (2) Graphite (3) Buckminster fullerene               (1) Diamond Diamond is a colourless transparent substance having extraordinary shining. Diamond is quite heavy. Diamond is extremely hard. It is the hardest natural substance known. Diamond does not cunduct electricity. Diamond burns on strong heating to form carbon dioxide. If we burn diamond in Oxygen , then only CO2 gas is formed and nothing is left behind. This shows that diamond is made up of carbon only. Structure of Diamond -  A Diamond crystal is a very big molecule of carbon atoms. Each carbon atom in the diamond crystal is linked to four other carbon atoms by strong covalent bonds. The four surrounding carbon atoms are at the four vertices of a regular tetrahedro

        Newton's laws of motion Newton has given three laws to describe the motion of bodies. These laws are known as Newton's laws of motion. The Newton's laws of motion give a precise definition of force and establish a relationship between the force applied on a body and the state of motion acquired by it. Newton's first law of motion - Newton's first law describes the behaviour of such bodies which are in a state of rest or of uniform motion in a straight line.          According to Newton's first law of motion -  A body at rest will remain at rest, and a body in motion will continue in motion in a straight line with a uniform speed, unless it is compelled by an external force to change its state of rest or of uniform motion.     It should be noted that by saying an external force, we mean a force from outside the body.      Let us take some examples to make the first law of motion more clear.     Suppose a book is lying on the table. It is at res

                         Cell  Cell -   The cell is the fundamental unit of life. All plants and animals are made up of cells. Cell is the microcosm (having a definite boundary with in) which constant chemical activities and flow of energy proceed. Cell is the structural and functional unit of all organisms.       The body of an organism may contain one cell as in Unicellular organisms. Each cell has the capacity to perform all vital activities like nutrition, growth, respiration, irritability, movement and reproduction etc. Discovery of cell - The cell was discovered by the scientist Robert Hooke in 1665, when he worked on the wooden cork. He cut the thin slices of wooden cork and see these thin slices of cork in the self made microscope. Then he saw the honey comb like structures . These structures are called cell by the scientist Robert Hooke in 1665. **  The cell which is discovered by the scientist Robert Hooke was a dead cell.  ** The first living cell (B

Real images and virtual images  (1) Real images-   The image which can be obtained on a screen is called a real image .  In a cinema hall , we see the images of actors and actresses on the screen. So, the images on a cinema screen is an example of real images. A real image is formed when light rays coming from an object actually meet at a point after reflection from a mirror ( or refraction through a lens ). A real image can be formed on a screen because light rays actually pass through a real image. Real images can be formed by a concave mirror. A convex lens can also form real images. (2) Virtual images-  The image which cannot be obtained on a screen is called a virtual image . A virtual image can be seen only by looking into a mirror ( or a lens) . The image of our face formed by a plane mirror cannot be obtained on a screen, it can be seen only by looking into the mirror. So the image of our face in a plane mirror is an example of virtual image. Virtual images are

                    Ohm's law  Ohm's law gives a relationship between current and potential difference. According to Ohm's law -      At constant temperature, the current flowing through a conductor is directly proportional to the potential difference across its end.         If I is the current flowing through a conductor and V is the potential difference ( or voltage) across its ends,then according to Ohm's law -              I ~ V   ( At constant temperature)       or,  V~ I       or,   V =  R  ×  I Where R is a constant called       " resistance'' of the conductor.  The SI unit of resistance is ohm. The value of this constant depends on the nature, length,are a of cross - section and temperature of the conductor.                                       V          Resistance R = --------                                        I The above equation is a mathematical expression of Ohm's law.

        Apiculture ( Bee Keeping)  Bee keeping or Apiculture ( L. apis = bee, culture= cultivate ) is the rearing, care and management of honey bees for obtaining honey, wax and other substances. Honey is known to have medicinal value. It is found to be quite useful in the treatment of various disorders of human beings related to digestion, dysentery, vomiting and stomach or liver ailments.              Bee keeping being ,a low investment enterprise, has become a favourite source of some extra income for the  farmers .Bee keeping is also helps in cross pollination of flowers. Products obtained from Apiculture -  (1) Honey -   Honey is a sweet, viscous edible fluid containing sugars , water, minerals, vitamins, amino acids, enzymes and pollen. Sugars present in honey include levulose , dextrose, sucrose and dextrin. Minerals of honey are calcium, iron, phosphate and manganese. The colour,flav fla and odour of honey usually depends on the flowers from which nectar is gathered.

                       Acids * Acids are those compounds    which gives Hydrogen ions (H+ ion) in aqueous solutions. For example-        HCl --------> H+    +  Cl`        (aq)            (aq)       (aq) * Acids are those compounds which makes hydronium ions in aqueous solutions. For example-           HCl --------> H+    +  Cl`        (aq)            (aq)       (aq) H+  +   H2O ------->  H3O+                            (Hydronium ion) * Acids are those compounds which is reacts with bases and form salts and water. For example- NaOH  +  HCl -------> NaCl +H2O (Base)     (Acid)      (Salt)   (Water) * Acids are those compounds which are bitter in taste.    For example- citric acid , lactic acid etc. *Organic acids and mineral acids- (1) Organic acids-   The acids present in plant materials and animals are called organic acids.  For example- Acetic acid, formic acid etc. (2)Ino rganic acids-   The acids prepared from the

                  Force  When we want to open a door, we have to push the door handle. And when we want to close the door, we have to pull the door handle with our hands. This means that to move a body or an object, it has either to be pushed or pulled.           A push or pull on a body is called force. The direction in which a body is pushed or pulled is called the direction of force.         Forces are used in our everyday actions like pushing, pulling, lifting, stretching, twisting and pressing. For example - A force is used when we push (kick) a football.   Effects of force -       A force cannot be seen. A force can be judged only by the effects which it can produce in various bodies or objects around us . A force can produce the following effects -  1) A force can move a stationary body. 2) A force can stop a moving body. 3) A force can change the speed of a moving body. 4) A force can change the direction of a moving body. 5) A force can change the sha

        Dalton's atomic theory  The theory that all matters is made up of very tiny indivisible particles (atoms) is called atomic theory of matter. Dalton put forward his atomic theory of matter in 1808.       The various postulates or assumptions of Dalton's atomic theory of matter are as follows- (1) All the matter is made up of very tiny particles called atoms. (2) Atoms cannot be divided. (3) Atoms can neither be created nor be destroyed. (4) Atoms are of various kinds. There are as many kinds of atoms as are elements. (5) All the atoms of a given element are identical in every respect, having the same mass, size and chemical properties. (6) Atoms of different elements differ in mass, size and chemical properties. (7) Chemical combination between two or more elements consists in the joining together of atoms of these elements to form molecules of compounds. (8) The numbers and kind of atoms in a given compound is fixed. (9) During chemical combina

               The Gas law  (A) Boyle's law -  This law is given by the scientist Robert Boyle in 1662. According to this law-   The volume of a given mass of a gas is inversely proportional to its pressure provided the temperature remains constant.                                                                                 1  v     =   -----            ( at constant                     p          temperature )  Or,     pv =  k = constant Let the pressure and volume of any  gas is p   and V  and the                        1           1   pressure and volume    of the same  amount of the same gas be p  and v      then -  2           2     p   v    =   p    v  = constant       1    1         2    2  (B) Charles' law-    This law is given by the scientist J. Charles in 1787. According to this law- At constant pressure, the volume of a given mass of a gas is directly proportional to its absolute temperature.      V   ~  T  (at

Laws of chemical combination (1)Laws of conservation of mass-  This law is given by the French scientist A. Lavosier in 1774.            According to this law- In any physical or chemical change the total mass of the products is always equal to the total mass of the reactants. This law is also represents as - Matter is neither be created nor be destroyed in any physical or chemical change but it transformed into one form to another form.     For example-    2H2O  ------> 2H2  + O2   36 gram      4 gram   32 gram (2)Law of constant proportion- This law is given by the French scientist Proust in 1799.            According to this law- In any chemical compound , the elements presents in the compound are always present in a fixed proportion by mass.    For example- (a)In the compound CO2 the ratio of Carbon and Oxygen is always found in the 3:8 by mass. (b)  In the compound H2O the ratio of Hydrogen and Oxygen is always found in the 1:8 by mas

वांट हॉफ कारक(van't Hoff factor ) वांट हॉफ (1886) ने विलेय पदार्थो के आणविक संयोजन तथा वियोजन का विस्तृत अध्ध्यन किया तथा विलेय पदार्थ के विलयन में संयोजन या वियोजन की सीमा को व्यक्त करने के लिए एक कारक i की कल्पना की | इस कारक को वांट हॉफ कारक कहते हैं | इसे निम्न प्रकार परिभाषित किया जा सकता है - किसी अणुसंख्य गुणधर्म के प्रायोगिक मान (observed value ) तथा सामान्य मान (calculated value ) के अनुपात को वांट हॉफ कारक i कहा जाता है | गणितीय रूप में,      किसी अणुसंख्य गुणधर्म का प्रायोगिक                       मान (observed value ) i =  --------------------------------------------       किसी अणुसंख्य गुणधर्म का  सामान्य             मान (calculated value )                         ∆                           obs  या,        i =    ------------                         ∆                           cal वाष्प दाब में अवनमन के लिए,                    (∆p)                           obs           i =    ------------                    ( ∆p)                            

  उत्प्रेरण (Catalysis )  रासायनिक अभिक्रियाओं की गति किसी विशिष्ठ पदार्थ की थोड़ी सी मात्रा की उपश्थिति से प्रभावित हो सकती है | इस प्रकार के पदार्थो को उत्प्रेरक कहा जाता है तथा इस घटना को उत्प्रेरण कहते हैं | उत्प्रेरण पद को सर्वप्रथम बर्जीलियस ने सन 1836 में प्रयोग किया था | (A) धनात्मक उत्प्रेरण ( positive catalysis )-  वे उत्प्रेरक जो अभिक्रिया के वेग को बढ़ा देते हैं उन्हें धनात्मक उत्प्रेरक कहा जाता है तथा इस घटना को धनात्मक उत्प्रेरण कहते हैं | जैसे -                        Pt         2H2O2 --------> 2H2O + O2 (B) ऋणात्मक उ त्प्रेरण ( Negative  catalysis )-  वे उत्प्रेरक जो अभिक्रिया के वेग को घटा  देते हैं उन्हें ऋणात्मक उत्प्रेरक कहा जाता है तथा इस घटना को ऋणात्मक उत्प्रेरण कहते हैं | जैसे - टेट्रा एथिल लेड (TEL ) की उपश्तिथि द्वारा पेट्रोल का अपस्फोटन कम हो जाता है |       उत्प्रेरण के प्रकार ( Types of Catalysis ) (1) समांग उत्प्रेरण (Homogeneous catalysis )--    जब उत्प्रेरक व अभिकारक एक ही प्रावस्था में स्थित होते हैं तथा अभिक्रिया तंत्र पूर

फैराडे के विद्युत् अपघटन के नियम (Faraday's laws of electrolysis) माइकल फैराडे ने सन 1832 में  विद्युत् अपघटन का गहन अध्ययन किया और इलेक्ट्रोडो पर मुक्त उत्पादों की मात्रा व प्रवाहित विद्युत् धारा की मात्रा के बीच सम्बन्ध के लिए दो नियम दिए | इन्हे फैराडे के विद्युत् अपघटन के नियम कहते हैं | ये नियम निम्न हैं - (1) फैराडे का  विद्युत् अपघटन का प्रथम नियम -  विद्युत् अपघटन की प्रक्रिया में किसी इलेक्ट्रोड विशेष पर मुक्त या एकत्रित पदार्थ का द्रव्यमान विलयन में प्रवाहित की गयी विद्युत् धारा की मात्रा ( कुल आवेश ) के समानुपाती होता है |   यदि विलयन में विद्युत् (आवेश ) के Q कूलम्ब को प्रवाहित करने पर किसी इलेक्ट्रोड पर एक पदार्थ के W ग्राम मुक्त होते हैं , तो फैराडे के   विद्युत् अपघटन के  प्रथम नियम के अनुसार ,          आवेश = विद्युत् धारा × समय या ,       Q = I × t या ,        W = Z × I × t जहाँ Z एक स्थिरांक है , जिसे विद्युत् रासायनिक तुल्यांक कहते हैं | (2) फैराडे का  विद्युत् अपघटन का द्वितीय  नियम -   जब श्रेणीक्रम में जुड़े विभिन्न विद्युत् अपघट्यो के

अणुसंख्य गुणधर्म (Colligative properties ) विलयनों के वे गुण जो विलायक की एक निश्चित मात्रा में उपश्थित विलेय कणो की संख्या पर निर्भर करते हैं किन्तु विलेय की रासायनिक प्रकृति पर निर्भर नहीं करते हैं, अणुसंख्य गुणधर्म कहलाते  हैं |            विलयनों के महत्वपूर्ण  अणुसंख्य गुणधर्म निम्न हैं - (1) वाष्पदाब में सापेक्ष अवनमन  (2) क्वथनांक में उन्नयन  (3) हिमांक में अवनमन  (4) परासरण दाब      (1) वाष्पदाब में सापेक्ष अवनमन -  किसी वाष्पशील विलायक में एक अवाष्पशील विलेय को मिलाने पर उसके वाष्पदाब में कमी उत्पन्न होती है | यदि किसी शुद्ध विलायक का वाष्पदाब p° तथा विलयन का वाष्पदाब p हो तो         वाष्पदाब में अवनमन =p° - p तथा  वाष्पदाब में सापेक्ष अवनमन = p° - p                                                  --------                                                    p° राउलट के नियम के अनुसार , p° - p  --------- = x (विलेय )     p°  (2) क्वथनांक में उन्नयन -   किसी विलेय पदार्थ को किसी विलायक में मिलाने पर उस विलायक के क्वथनांक में वृद्धि हो जाती है , इसे

Some important model of Atom   (कुछ महत्वपूर्ण परमाणु मॉडल ) (A) टॉमसन का परमाणु मॉडल -  जे. जे. टॉमसन ने 1904 में परमाणु का प्रथम मॉडल दिया | इसे टॉमसन का तरबूज मॉडल भी कहते हैं | इसके अनुसार परमाणु इलेक्ट्रोनो तथा धन आवेशित द्रव्य से मिलकर बना है | परमाणु गोलाकार  अति सुक्ष्म तथा विद्युत् उदासीन कण है |परमाणु में धन आवेशित द्रव्य समान रूप से फैला हुआ है तथा इलेक्ट्रान धन आवेशित द्रव्य में इस प्रकार धँसे हुए हैं जैसे तरबूज में बीज धँसे रहते हैं | (B) रदरफोर्ड का परमाणु मॉडल -  अर्नेस्ट रदरफोर्ड ने  अल्फ़ा - कणों के प्रयोग से नाभिकीय मॉडल दिया | इस मॉडल के अनुसार - 1) परमाणु गोलाकार, अति सूक्ष्म तथा विद्युत् उदासीन कण है | 2)परमाणु का समस्त धनावेश तथा लगभग समस्त द्रव्यमान उसके केंद्र में एक सूक्ष्म आयतन में संचित रहता है | 3)परमाणु में इलेक्ट्रान तथा प्रोटोन होते हैं |परमाणु में  प्रोटोन उसके नाभिक में तथा इलेक्ट्रान  नाभिक के बाहर होते हैं | 4)परमाणु में इलेक्ट्रान नाभिक के चारो ओर जिन पथो पर घूमते हैं, उन्हें इलेक्ट्रोनो की कक्षाएं कहते हैं |इलेक्ट्रान नाभिक के चार