General Science Force and Motion

Exercise: 9.2 Q1. What are machines? Ans: Machines are devices which are used to reduce the human effort and make the work easier. Q2. Name three objects that you exert force on, while doing school work. Ans: Pencil, Eraser, Sharpener. Q3. Name these. Ans: 1. Straight slanted surface: Inclined plane.         2. A rod that pivots at a fixed point pulley. 3. An inclined plane wrapped in spiral screw. 4. Double inclined plane Wedge. 5. Machine consisting of a grooved wheel that holds a rope wheel and axle. Q4. Complete the following concept map. Exercise : 9.4 Explain how atmospheric helps you drink throw a straw? Ans:...

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General Science Element, Compound & Mixture

EXERCISE 7.1: Q1. Define Matter Ans: Matter is any thing that has mass and occupies space. Q2. Complete the following concept map. Q3. How are compound different from elements? Ans: In elements all the atoms are identical while in compounds basic unit is a molecule. Which is composed of two or more different type of atoms. EXERCISE 7.2: 1 Ans: No, Hydrogen and oxygen are elements, and elements are the simplest substances. 2 Ans: (a) True    (b) False   (c) True 3. Elements Compounds Sodium+Chlorine Table salt (NaCl) Carbon+Oxygen Carbondioxide (CO2) Carbon+Hydrogen+Oxygen ...

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