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VSEPR THEORY: DEFINITION, POSTULATES OF THE VSEPR MODEL OR VSEPR THEORY What is VSEPR theory? Valance Shell Electron Pair Repulsion theory also called VSEPR theory was the theory given by Sidgwick and Powell. This theory describes the influence of the lone pair of electrons on the bonding electron and also predicts the shape of the molecules. This theory is based on the number of valance electrons present in the central atom of a molecule. Statement : "A molecule takes a shape that minimizes the repulsion between the bonding and non-bonding pair of an electron." Postulates of VSEPR theory: Following are the postulates of the VSEPR theory : 1 . In any covalent molecule, there is a central atom around which other atoms are arranged.  2 . The shape of the molecule is determined by the number of electron pairs present in the valence shell of the central atom. 3 . If the central atom of a molecule is surrounded by electron pair of dissimilar atoms then the molecule will have irre

PHYSICS ENTRANCE MODEL QUESTIONS FOR CLASS 11 1. Where does the Selective accumulation of iodine occurs in:     a) Intestine     b) Thymus     c) Thyroid     d) Liver     Ans: c 2. What is another name for Sympathetic nervous system:     a) Central nervous system     b) Peripheral nervous system     c) Autonomous nervous system     d) None     Ans: c 3. Endocrine disorder leads to which one of the following?     a) Pneumonia      b) Jaundice       c) Typhoid      d) Goitre      Ans: d 4. Where does the digestion of cellulose takes place in the rabbit:     a) Colon      b) Ileum     c) Caecum      d) Rectum     Ans: c 5. What is the structure that prevents the entry of food into human's respiratory tract?      a) Larynx     b) Pharynx     c) Glottis     d) Epiglottis      Ans: d 6. What are Fat soluble vitamins from the following:     a) A, D, & E     b) B, C, and D     c) B and C     d) A, B and C     Ans: a 7. Rickets is a kind of:      a) Communicable disease      b) Deficie

SIMPLE HARMONIC MOTION: DEFINITION, EQUATIONS, RELATIONS EXECUTING SIMPLE HARMONIC MOTION What is Simple Harmonic Motion? Simple Harmonic Motion (SHM) is defined as a to and fro of motion of an object about a mean position. The motion of a body is said to be simple harmonic if its acceleration is always, a) directed towards a fixed point (mean position) b) directly proportional to the distance from a fixed point.   When a body is displaced in simple harmonic motion , a restoring force is set up. Due to this restoring force, the body comes back to its equilibrium, it gets kinetic energy and the body moves away from the equilibrium position. In this way, the body continuously oscillates back and forth about the mean position. Therefore, the motion is said to be a Simple Harmonic Motion (SHM) . Relation between acceleration and displacement of a particle executing simple harmonic motion (SHM): Consider a particle having mass 'm' moving with a uniform circular motion w

COPPER EXTRACTION: EXTRACTION OF COPPER FROM COPPER PYRITE Principle Copper is extracted mainly from its copper pyrite ore by means of the self-reduction process. Following are the steps involved in the extraction: 1. Crushing : The big lumps of copper pyrite ore is crushed in two smaller pieces by using a Jaw crusher. 2. Pulverzition : The crushed ore is further crushed and changed into powder form by using a Stamp mill. 3. Concentration : The concentration is done by Froth Floatation Method. In this method, the mixture of water and pine oil is taken on the vessel in which the powder ore from the pulverization process is mixed. The sulphide ore is wetted by pine oil and the impurities are wetted by water and settle down at the bottom of the vessel. 4. Roasting : It is done in the Reverberatory furnace by the supply of hot air. In this process, the moisture is removed and the volatile impurities are removed as an oxide. In this process, the sulphide ore is converted into oxide ore by m