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Property of Sound Waves that Sound needs Material Medium to Travel

The sound waves need material medium to travel because they travel by the vibrations of particles of the medium. The material medium is gas, liquid and solid.  Sound waves are called mechanical waves as they need a material medium for their travel.  An activity described below tells that sound can not travel through vacuum. The …

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Work, Energy, Power – Question and solution

A body of mass 20 kg is projected vertically upwards with a velocity of 20m/s. Find – (a) its potential energy at the starting point         (b) its kinetic energy at the starting point         (c) its potential energy at the highest point          (d) its kinetic energy at the highest point. Answer – (a) its potential energy …

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Introduction to Python

Pythons are very powerful and very flexible creatures, as we all know. In the same way, we find that the language Python is also very powerful and flexible. Python is an open source, object-oriented, high level programming language which was developed by Guido van Rossum in 1991. The language is based on the ABC language(yes …

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Previous Year’s CBSE Board Questions – Life Processes – Transportation

Transportation What will happen to a plant if its xylem is removed? (Delhi 2009, 1 mark) Need clues – Click here (a) Draw a sectional view of the human heart and level on it – Pulmonary arteries, vena cava, left ventricle.(b) Why is double circulation of blood necessary in human beings? (AI 2009, 5 marks) …

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Previous Year’s CBSE Boards Questions – Soaps and Detergents (Carbon and its Compounds)

Soaps and Detergents – Give reasons for the following observation – Use of synthetic detergents causes pollution of water. (1/3 mark, Delhi 2009) Need clue – Click Here Explain the cleansing action of soap. (2/5 marks, Foreign 2009) Need clue – Click Here Why does micelle formation take place when soap is added to water? …

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Some Important Carbon Compounds -Ethanol and Ethanoic acid

ASSESSMENT – CLICK HERE Previous Year’s CBSE Board Questions -Some Important Carbon Compounds – Ethanol and Ethanoic acid   [googlepdf url=”https://freakgenie.com/wp-content/uploads/2019/02/carbon-compd-ethanol-and-ethanoic-acid.pdf” width=”100%” height=”2560″] ASSESSMENT – CLICK HERE Previous Year’s CBSE Board Questions -Some Important Carbon Compounds – Ethanol and Ethanoic acid

Previous Year’s CBSE Board Questions -Some Important Carbon Compounds – Ethanol and Ethanoic acid

Some Important Carbon Compounds – Ethanol and Ethanoic acid 1. Write the name and molecular formula of an organic compound having its name suffixed with ‘-ol’ and having two carbon atoms in its molecule. Write balanced chemical equation to indicate what happens when it is heated with excess of conc. H2S04 and the name of …

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Difference between Asexual Reproduction and Sexual Reproduction

There are two methods of reproduction – (A) Asexual reproduction (B) Sexual reproduction (A) Asexual reproduction It involves only one individual (single parent). It takes place without gametes (sex cells) and fertilization. Cells divide mitotically. It is a simple process of cell division as shown below. Offsprings are genetically identical to the parents. E.g. Spirogyra …

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Heredity

Heredity is the passing of characters or traits from its parent or ancestors to their offspring. The study of heredity in biology is called genetics. It explains that organisms resemble each other because they arise from common ancestor. The offspring of cats are cats, fish are fish and humans are humans only. Trait – A …

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Force and Laws of Motion – Balanced and Unbalanced Force, Inertia, Types of Inertia   

When the sum of forces becomes zero, the forces balance each-other and the forces are called balanced forces. Activity – We take a box and tie two strings to it in opposite direction. One string is at end A and other string is at end B. When we pull string at A, the box moves …

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FORCE AND LAWS OF MOTION / THE LAWS OF MOTION – SUMMARY

Summary – If the resultant of all the forces acting on a body is zero, the forces are called balanced forces. If the resultant of all the forces acting on a body is not zero, the forces are called unbalanced forces. An unbalanced force acting on a body gives it an acceleration. Force is an …

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Common Behaviour of Acids and Bases

In the following section, we will find the answers of  following questions- (i) All acids have similar chemical properties. All bases have similar chemical properties. What   lead to this similarity in properties? (ii) How acids and bases are different chemically?        Group A                                                  Group B ACIDS                                                   BASES                                             Hydrochloric acid (HCl)                      Sodium hydroxide …

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Importance and Limitations of Modern Periodic Table

Importance of Modern Periodic Table 1. Based on atomic number –     The arrangement of elements in modern periodic table is according to their increasing order of atomic number. Atomic number increases by 1 unit (not fractional) in going from one element to the next element and equal to the number of electrons. Thus, the …

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Arrangements in Modern Periodic Table    (Long Form of Periodic Table)    

 The arrangement  in periodic table is given by Bohr so it is also known as Bohr’s table or Long form of periodic table. This table is prepared on the basis of – (a) increasing order of atomic number or electronic configuration. (placed in a period) (b) same number of valence electron/electrons. (placed in one group) …

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INTRODUCTION TO MODERN PERIODIC TABLE

The modern periodic table of elements is based on Mendeleev’s observations. The only difference is instead of being organized by atomic masses, the modern table is arranged by atomic number (Z). Henry Moseley, in 1913, found that atomic number is more fundamental property of an element than its atomic mass. Atomic number helps in arranging …

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Introduction to Organic Chemistry and Vital Force Theory

     ♦      Earth crust has only 0.02% carbon in the form of minerals (e.g. – carbonates, bicarbonates, coal, petroleum etc.) and atmosphere has 0.03% carbon dioxide. Inspite of its availability in such a small amount, it is highly important for our lives.                                                               ♦     Except water most of …

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WHAT IS FORMULA UNIT MASS OR FORMULA MASS?

The compounds which are formed by ions are called ionic compounds. In general, cations are made by metals and anions are made by non-metals. So, it can be understood as compounds made by metals and non-metals are ionic compounds. Examples – Al2(SO4)3, CaCl2, K2SO4, KNO3, CaCO3, NaCl, MgCl2 etc. Read more – Law of Conservation of …

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How do you Write Chemical Formula for an Ionic Compound?

Rules for writing a chemical formula  Write down the symbols of the ions (cation and anion) involved. Write the symbol of cation first (L.H.S) followed by the symbol of anion (R.H.S.). Write the valency of each ion. Interchange the valencies of the ions and write as the subscript. Write them close together and ignore ‘1’ …

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RULES FOR WRITING A CHEMICAL FORMULA OF SIMPLE COMPOUNDS

Chemical formula is a symbolic representation of a molecule’s composition. It indicates – (a) the elements that are present in the compound and (b) the ratio of these elements in the compound. A chemical formula is also called molecular formula. The symbols in the molecular formula tell us about the elements and the subscript tells …

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Problems / Numericals based on Mole Concept (Atomic Mass/ Molar Mass/ Avogadro number)

Formulas in brief –               Mass = Molar mass x Number of moles  Number of moles = Given number of particles / Avogadro number      Number of particles = (Given mass / molar mass) x Avogadro number          (from 1 and 2)  If one carbon atom has a mass of 12 atomic mass units and one magnesium atom has …

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Mole Concept – Introduction, Importance and Formulae

Introduction  The structure of matter can be one of the following – atoms → molecules → bulk compound or element atoms → bulk element atoms → ions → bulk ionic compound It clearly shows that the masses that are measured in the laboratory are masses corresponding to large numbers of tiny atoms or molecules. Logically …

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Importance of Mendeleev’s Periodic Table

Read First – Mendeleev’s Periodic Table (1) Systematic Study of the elements Mendeleev’s periodic table was developed in accordance to- (a) increasing atomic masses. (b) grouping of similar elements together. By the way, the study of elements became quite simpler, as if properties of one element in a particular group were known, properties of others …

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DISCOVERY OF CHARGED PARTICLES IN MATTER – Electron, Proton and Neutron

Read – Structure of the Atom / Inside the Atom – Summary Discovery of Electron – During 1890s’ many scientists performed experiments using cathode ray tubes.  A cathode ray tube or discharge tube is made of glass from which most of the air has been removed. Such a cathode ray tube can be seen in figure.  …

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Electric Symbols and Electrical Circuits – Introduction and Quiz

Read First – Electric Current Circuit is a continuous path consisting of conducting wires and other resistances between the terminals. Electric circuit is a continuous path made by conducting wires, devices such as resistances, capacitors etc. and voltage sources. A continuous / closed path consisting of conducting wires and other resistances between the terminals of a …

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Defects of Eyes and their Remedies     

Read – Human Eye and Colorful World  -Eye -Structure Some people can not see clearly objects due to loss of power of accommodation of eye. Such problem may be due to – 1. weakening of ciliary muscles                                                                                                          2. change in size of eyeball                                                                                                     3. Irregularity on the surface of cornea                                                                                               4. Formation of membrane …

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Heredity and Evolution / Mapping our Genes – Variation

  [pullquote-right]“The act or process of changing (in genetics) in the characters or traits in an individual from the group to which it belongs or deviation in characters of the offspring from those of its parents is called variation.”[/pullquote-right]       Heredity and Evolution – Summary     During reproduction, the organism uses its …

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Control and Coordination in Animals and Plants – Introduction

Read more – Life Processes / Life’s Internal Secrets How do Organisms Reproduce?/ The Life Cycle Heredity and Evolution Why do you quickly remove your fingers on touching a hot object? Who controls and coordinates your heart to relax and contract continuously? What enables you to learn, think, analysis and remember? How can you watch T.V. …

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Life Processes – Nutrition

Read First – Life Pocesses – Introduction Food contains several components known as nutrients. “Nutrients are chemicals- inorganic as well as organic that an organism needs to live and grow”. They are obtained from an organism’s surroundings. There are six major classes of nutrients classified as -proteins, vitamins, water, carbohydrates, dietary fiber, fats and minerals …

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Mendeleev’s Periodic Table

Read first – Periodic Classification of Elements – Inroduction, Dobereiner’s Traids Newlands’ Law of Octaves A most important contribution on arrangement of elements after Newland was given by a Russian Chemist called Dmitri Mendeleev. Before discussing Mendeleev’s periodic table, we should learn the meaning of following terms – Periodic Table –  It is a chart …

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What is the Versatile Nature of Carbon?

Why are carbon and its compounds so important or special from compounds of all the other more than hundred – odd elements of the periodic table?                   This is because – (a) The number of compounds that contain carbon is many time greater (due to catenation) than the  number of compounds that do not contain carbon. …

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Physical Properties of Non-Metals

Read First- Physical Properties of Metals Non-metals Physical state – Non-metals exists in all three physical state. Carbon, sulphur, phos-phorous etc. are solids. Oxygen, nitrogen, chlorine etc. are gases whereas bromine is a liquid.  Lustre – Non- metals are non-lustrous substances.            Exception – Diamond, graphite (allotropes of carbon) and iodine are lustrous in appearance. Hardness …

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Gravitation – Summary

Latest CBSE syllabus topics – Gravitation – Gravitation, universal law of gravitation, force of gravitation of the earth (earth’s gravity), acceleration due to gravity, mass and weight, free fall. Flotation – Thrust and Pressure, Archimedes’ Principle, Buoyancy, Elementary idea of relative density. Latest Maharashtra SSC Board syllabus topics – The Pull of the Earth – …

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Basics of Programming

I know that many face problems in coding and coding is not everyone’s cup of tea however one can benefit from the following steps. Also, coding is like maths more you practice better coder you become. So, without any further ado let’s begin. 1. Read the problem carefully. This step is essential while approaching any …

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Magnetic Effects of Electric Current -To see the effect of magnetism of bar magnet on iron fillings

Magnets are fancy of children. So many toys use magnets. However magnets have many applications. Magnet attracts iron, nickel and cobalt objects , the unlike poles of magnets attract each other however the like poles of magnets repel each other. Magnets are natural magnets (permanent magnets) and man-made magnets. Earth as magnet – A freely …

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HUMAN EYE AND COLOURFUL WORLD / WONDERS OF LIGHT PART – I

Eye is the most important sense organ. It is the sense organ through which we can see the world and we can watch the different colours. Eye is similar to camera in the sense that the light enters through cornea and image is formed on a light sensitive screen called retina inside the eye. There …

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How do Organisms Reproduce? / The Life Cycle – Summary

Reproduction –  A process by which a living organism is able to produce more of its own kind. It is of two types- asexual reproduction and sexual reproduction. Asexual reproduction –  Production of an offspring from body parts other than the reproductive organs. In this, only one organism is involved, no gametes are produced and …

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Heredity and Evolution / Mapping Our Genes -Summary

Summary – Passing down of characters / traits from parents to children is called heredity. Children of same parents differ because they possess different combinations of parental genes. These difference are termed variations. We are all human beings but can be distinguished easily from each other due to variation. Heredity and variation are due to …

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Control and coordination / The Regulators of Life – Summary

• Control is systematic regulation of various activities. Coordination is the orderly execution of the processes. • Homeostasis, in biological terms means that the body is maintaining internal equilibrium to adjust itself internally and physiologically, in response to the external environmental changes. Read more – Life Processes / Life’s Internal Secrets How do Organisms Reproduce?/ The Life …

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Improvement in Food Resources / Quality Food, Quality Life -Summary

Summary –  Between 1968-1978, a major improvement occurred in Indian agriculture and animal husbandry.  It was veritable revolutions that are known as the Green Revolution and White revolution.  On the basis of seasons, crops have been classified as – (a) Kharif crops – These are the crops grown during the rainy season from June to …

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Why Do We Fall Ill / Highway to Health – Summary

Health is a state of complete physical, mental and social well being and not merely the absence of disease. The conditions necessary for good health are – (i) Good physical and social environment. (ii) Good economic conditions. (iii) Social equality and harmony. Thus, for maintaining good health, balanced diet, hygienic surroundings, proper habits, exercise and …

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Diversity in Living Organisms / Life Around You : Summary / Introduction

Taxonomy  is the branch of biology for the study of classification of organisms following certain rules or principals. Systematics (systema – order) – The camparative study of organisms on the basis of morphology, anatomy, ecology, physiology, biochemistry etc. is known as systematics. Systematics have three fields (i) Nomenclature (ii) Classification (iii) Taxonomy Classification – grouping …

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Structure of the Atom / Inside the Atom – Summary

Latest CBSE syllabus topics –                                                                                                          Structure of atom – Electrons, protons and neutrons ; Isotopes and Isobars. Latest Maharashtra SSC Board syllabus topics – Inside the atom – Historical background ; Rutherford’s scattering experiment ; Distribution of electrons in orbits ; Electronic configuration of elements ; Isotopes and their applications. Summary – E. Goldstein discovered …

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Atoms and Molecules / Counting Matter- Summary, Introduction

 Summary – ♦ Laws of  Chemical Combination – (a) Law of Conservation of Mass – Mass can neither be created nor be destroyed in a chemical reaction. (b) Law of Constant Proportions – In a chemical substance, the elements are always present in definite proportions by mass. ♦ Dalton’s atomic theory – All matter is composed …

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Newlands’ Law of Octaves

Read First – Dobereiner’s Traids Read More – CHEMISTRY – MATTER / ATOMS AND MOLECULES / STRUCTURE OF THE ATOM / CHEMICAL REACTIONS AND EQUATIONS / ACIDS, BASES AND SALTS / METALS AND NON-METALS / CARBON AND ITS COMPOUNDS / PERIODIC CLASSIFICATION OF ELEMENTS   After as Dobereiner’s Traids was ruled out, an English chemist J.A.R. Newlands observed similarities in physical and chemical properties of every …

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PERIODIC CLASSIFICATION OF ELEMENTS – Introduction, Dobereiner’s Triads

  INTRODUCTION Till 18th centuries, only 30 elements were known. By the year 1865, 63 elements were discovered. Till date , 118 elements have been discovered and many more may be known in future. Read More – CHEMISTRY – MATTER / ATOMS AND MOLECULES / STRUCTURE OF THE ATOM / CHEMICAL REACTIONS AND EQUATIONS / ACIDS, BASES AND SALTS / METALS AND NON-METALS / CARBON …

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Physical Properties of Metals

Elements are broadly classified on the basis of their physical and chemical properties-                                (a) Metals (b) Non-metals Besides metals and non-metals, there is a third group of elements called metalloids which show properties intermediate to metals and non-metals. E.g.- silicon (Si), germanium (Ge), arsenic (As), antimony (Sb) and tellurium (Te). There are very few …

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Light – Refraction of Light

Refraction is the bending (change in the direction) of a wave (light or sound). When a light ray passes from one transparent medium to another, it changes speed and bends. Example : Light traveling from air and going into water – half submerged straight stick or pencil into water.                        The stick appears bent …

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Life Processes / Life’s Internal Secrets -Introduction

Living and Non-living – If something is living, it will carry out all the seven functions which are movement, reproduction, sensitivity, nutrition, excretion, respiration and growth.  Some non living things may show one or two of the seven characteristics of living things but not all of them. For ex.-car moves, crystals grow in size during …

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Balancing of an Unbalanced Chemical Equation in 5 Easy Steps

Balancing of an unbalanced chemical equation means making the number of atoms of various elements equal in reactants and product in an equation. It is important to note that during balancing a reaction, the formula of a compound (or the subscript of the symbol) must not be changed. For e.g. – H2  +  O2  →  H2O Here, …

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How to write a Chemical Reaction in Chemical Equation Form?

The description of a chemical reaction in sentences is quite long and time consuming. To make it shorter, a chemical reaction can be written in word equation form. For e.g. – When a magnesium ribbon burns in air / oxygen, it gives magnesium oxide. Activity – 1  Word equation – Magnesium + Oxygen → Magnesium Oxide …

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Nature of Matter (on the basis of their Chemical Properties)

Read First – Can Matter change its States? States of Matter What is Matter? What is its Characteristics? [dropcap]Matter[/dropcap] is everything around us which is made up of tiny particles. In the previous posts, we have learnt classification of matter into solid, liquid and gas, on the basis of their physical properties. In the following post, …

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Why do we fall ill / Highway to Health – Summary

Summary – Health is a state of complete physical, mental and social well being and not merely the absence of disease. The conditions necessary for good health are – (i) Good physical and social environment. (ii) Good economic conditions. (iii) Social equality and harmony. Thus, for maintaining good health, balanced diet, hygienic surroundings, proper habits, …

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Outer membrane of Cell – Cell membrane / Plasma membrane

 Outer membrane of Cell [A] Cell membrane / Plasma membrane Position – This is the outer covering of the animal and plant cells which encloses the mass of cytoplasm and gives separate identity to the cell. Characteristics – (i) Selectively permeable so allow only selected substances to pass in (water, salt, oxygen) and out (carbon …

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What is Matter? What are the Characteristics of Matter?

Matter is everything around you which is made up of particles. It has mass and occupies space. Mass is a physical quantity which expresses the amount of stuff in an object. The space inside the container that is occupied by matter is its volume. Early Indian philosophers classified matter in the form of five basic elements – the …

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What is Chemistry? What are the main branches? What is its Importance and Scope?

[dropcap]W[/dropcap]When you hear the word ‘chemistry,’ there are certain images that come to mind – a colorful lab, colored liquids, different smells – good or bad (Ugh!!), glass wares, test tubes, the periodic table, molecules, maybe even some cool explosions (BOOM!), magic tricks  in a movie…..But chemistry is so much more than these things… in fact, …

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Cell : The Fundamental Unit of Life

Introduction If something is living, it will carry out all the seven functions which are [highlight]movement, reproduction, sensitivity, nutrition, excretion, respiration and growth[/highlight]. Some non living things may show one or two of the seven characteristics of living things but not all of them. For ex.-car moves, crystals grow in size during crystallization process. [pullquote-right]“Thus, the …

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A CHEMICAL REACTION IS CHARACTERIZED BY EVOLUTION OF A GAS AND BY EVOLVING HEAT (EXOTHERMIC REACTION).

Take a few zinc granules in a conical flask. Add dilute hydrochloric acid (HCl) or sulphuric acid (H2SO4) in the conical flask. (a) What do you observe ? (b) Touch the conical flask and observe any change in its temperature ? Objective – A chemical reaction characterized by evolution of a gas and by evolving heat …

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COMBINATION REACTION

Slowly add water in a small amount of calcium oxide or quick lime containing in a conical flask. Touch the beaker. Do you feel any change in temperature ? Objective – Combination reaction with heat change. Inference – Calcium oxide (CaO) reacts vigorously with water and form a single product, calcium hydroxide (slaked lime). CaO(s) + H2O …

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IN A CHEMICAL REACTION, ORIGINAL SUBSTANCE LOSES ITS NATURE AND IDENTITY

Objective– To understand a chemical reaction. Procedure – Take a magnesium ribbon. Clean it by rubbing with sand paper. (a) Why should magnesium ribbon be cleaned before burning in air ? Hold it with a pair of tongs. Burn it in the flame of a burner. Collect the ash so formed in a watch glass. Precaution …

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List of Polyatomic Ions and Charges

 Simple ions – The ions which are formed from single atom carrying a positive or negative charge are called simple ions or mono-atomic ions. Example – Na+, Cl–, O-2, Al+3, N-3(nitride), Mg+2, Ca+2, Cu+2, Fe+2etc. Polyatomic ions -Polyatomic ions or compound ions are molecules formed from groups of atoms bonded together that carry a positive …

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IONS – Anions and Cations

Atoms are neutral; they contain the same number of protons (positive particles) and electrons (negative particles). When the numbers of these subatomic particles are not equal, the atom is electrically charged and is called an ion i.e. ions are electrically charged atoms with extra electrons or missing electrons. It means ions are formed when atoms lose or gain …

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What is Matter?

Matter can be anything which occupy space and have mass. • On the basis of Physical state, matter can be divided into – (a) Solid (b) Liquid (c) Gas • On the basis of Macroscopic or bulk level, matter can be divided into – (a) Mixture – which are further divided into – (i) Homogeneous mixture (ii) Heterogeneous …

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Dalton’s Atomic Theory of Matter , Drawbacks and Importance

Read First – Law of Conservation of Mass Law of Definite Proportions / Constant Composition Mole Concept – Importance and formulas       John Dalton FRS (6 September 1766 – 27 July 1844) John Dalton was an English chemist, physicist, and meteorologist. He is best known for proposing the modern atomic theory and for his research into colour blindness, sometimes referred …

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How to solve Problems based on Law of Definite Proportions / Constant Composition

Read first – What is Matter? What is its Characteristics? States of Matter Law of Conservation of Mass Problems based on Law of Conservation of Mass Law of Definite Proportions / Constant Composition Mole Concept – Importance and formulas Problem 1 : One mole of  V2O5 contains 5 moles of oxygen atoms, as it is clear from …

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Law of Definite Proportions / Constant Composition

Read First – What is Matter? What is its Characteristics? States of Matter Law of Conservation of Mass Problems based on Law of Conservation of Mass The law of definite proportions or constant composition states that – “All pure samples of a particular chemical compound, the constituent elements are always combined in the same proportions …

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Laws of Chemical Combination – Law of Conservation of Mass

Read more – What is matter? What is its Characteristics? States of matter Mole Concept – Importance and formulas There are four laws of chemical combination. They are – 1. The law of conservation of mass 2. The law of constant (definite) proportions 3. The law of multiple proportions 4. The law of reciprocal proportions …

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Change of States of Matter – [B] Effect of change of Pressure

Read First – Can Matter change its States? States of Matter What is Matter? What is its Characteristics? [B] Effect of change of Pressure – Liquified petroleum gas . By increasing pressure, particles of matter can be brought close together. When we apply pressure on a gas enclosed in a cylinder, it  starts compressing and converts …

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A CHEMICAL REACTION IS CHARACTERIZED BY FORMATION OF A PRECIPITATE.

When a chemical reaction occurs, following observations help us to determine whether a chemical reaction has taken place. (1) Formation of a precipitate (2) Change in colour (3) Evolution of a gas (4) Change in state (5) Change in temperature or evolution / absorption of heat (6) Sound, light may be produced. (7) Change in …

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