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ATOM AND MOLECULES

  Introduction The idea of divisibility of matter was considered long back in India around 500 BC. An Indian philosopher Maharishi Kanad, postulated that if we go on dividing matter ( padarth ), we shall get small and smaller particles. he named these particles parmanu . Another Indian philosopher, Pakudha Katyayama, elaborate on this doctrine and said that these particles normally exist in a combined form which gives us various forms of matter. Around the same era, ancient Greek philosopher- Democritus and Leucippus suggested that if we go on dividing matter, a stage will come when particles obtained cannot be divided further. Democritus called these indivisible particles atoms . By the end of the 18th century, scientists recognized the difference between elements and compounds and naturally become interested in finding out how and why elements combine and what happens when they combine. Antoine L. Lavoisier laid the foundation of chemical sciences by establishing two important ...
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Short Answer Type Questions

 1. Fill in the blanks.  a) Matter is made up of small_________. b) The forces of attraction between the particles are _______ in solids, ______ in liquids and _________ in gases. c) Solid, liquid, and gas are called the three _______ of matter. Answer a) particles b) maximum, intermediate and minimum c) state 2. True/ False: a) Water at room temperature is a liquid. b) Atoms in a liquid are farther apart than the atoms in a gas. c) The molecules in a gas are in constant motion. Answer a) True b) False c) True
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Tonic Immobility

 Tonic Immobility Tonic immobility is the ability of animals to enter a state of paralysis so that they can avoid a predator. This is a natural behavior of animals in which they are temporarily paralyzed and unresponsive to external stimuli. The predator sees the paralyzed animal and though that he is dead. This can be called anti-predator behavior or animal hypnosis. The animals who show tonic immobility, they play dead, and playing dead is called thanatosis Animals who show tonic immobility Sharks  Rays Opossum Barred grass snake Burmeister's leaf frog Common swift (bird) Green-head ant Tonic Immobility in Humans Humans also show tonic immobility in extreme conditions such as extreme fear, sexual assault, or disaster. In any of these conditions, humans feel themselves becoming stiff, rigid, unable to move for some time or it can be throughout the trauma.
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IS MATTER AROUND US PURE

IS MATTER AROUND US PURE For a common person pure means having no adulteration. But for scientist, all these things are actually a mixture of different substances and hence not pure. For example - milk is actually a mixture of water, fat, proteins, etc. MIXTURE • Mixtures are constituted by more than one kind of pure form of matter, known as substance. • A substance cannot be separated into other kinds of matter by any physical process. • Example - dissolved sodium chloride (NaCl) can be separated from water by the physical process of evaporation but sodium chloride is itself a substance and cannot be separated by physical process into its chemical constituents. TYPE OF MIXTURES Depending upon the nature of the components that form a mixture, there are two types of mixtures. 1. Homogenous Mixture: A mixture that has a uniform composition throughout, known as a homogeneous mixture. Example: salt solution in water, sulphur solution in carbon disulphide, tap water, petrol, honey,...
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Matter in our Surroundings

 Matter in our Surroundings Matter  Air, water, stones, sand, clouds, pencils, books are made up of matter. Matter is everything in this universe that occupies space and has mass. Constituents of matter According to the early Indian philosopher, every living and non-living thing is made of five basic elements called the Panchtatava- air, water, earth, sky, and fire. therefore, matter is a composition of these five constituents. Physical Nature of Matter Is matter continuous or particulate? Matter is particulate in nature. This means that matter consists of particles as you can see in the microscopic image of a cube above.  For Example, if we put a drop of red colour in water the colour of the water turns red. This happens because the particles of red colour mix with the particles of water. What is the size of these particles? • The size of the particles of matter is very small. • They can be broken into further particles as well.  For Example, on dilution of a colo...
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