Category «Class 9 Science»

NCERT Class 9 Science Solution, Notes, Atoms and molecules

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Atoms and molecules Atoms are building block of all matter Atomic radius is measured in nanometres (1 m = 109 nm) Individual atoms can be observed using Scanning Tunnelling Microscopes Each element has a name and a unique symbol Rules for assigning symbols for atoms of various elements The abbreviation used to represent an element …

NCERT Class 9 Science Solution, Notes, Atoms and molecules

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Atoms and molecules 1.        Laws of chemical combination Law of conservation of mass: Mass can neither be created nor destroyed in a chemical reaction Law of constant proportion or Law of definite proportion:  In a chemical substance the elements are always present in definite proportions by mass 2.        Postulates of Dalton’s atomic theory All matter …