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Class 6th Ch 5 Separation of substances Written work

  Exercise Questions 1. Why do we need to separate different components of a mixture? Give two examples. Solution: When two or more substances are mixed together they form a mixture. Components of a mixture should be separated because some components may not be useful or may spoil the useful component of the mixture. Examples: Tea leaves are separated from the liquid with a strainer, while preparing tea Removal of stone pieces from wheat, rice or pulses by hand 2. What is winnowing? Where is it used? Solution: The method of separating the components from a mixture is known as winnowing. In this method, heavier and lighter components of a mixture are separated by wind or by blowing air. This method is used by farmers to separate lighter husk particles from heavier seeds of  grain. 3. How will you separate husk or dirt particles from a given sample of pulses before cooking? Solution: Husk and dirt particles are separated from pulses by winnowing. 4. What is sieving? Where is it used? Sol

Class 9th Science Ch 2 Revision Notes on Is matter around us Pure

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  Revision Notes on Is matter around us Pure What is a substance? Anything that cannot be broken into further particles by applying any physical processes is called a  Substance . Matter can be classified into two types of substances – Pure substances and Mixtures What is a pure substance? A substance that consists of only one type of particle is called a  Pure Substance .  For Example , Diamond, Salt, Sulfur, Tin.  What is a mixture? When we combine different substances into each other a mixture is formed.  For Example , Lemonade is a mixture of three substances, Lemon Juice, Sugar and Water. Which of these is a mixture or a pure substance? Water, Copper, Chocolate cake, Hydrogen, Soil, Air Mixture – Chocolate cake, Soil, Air Pure substance – Water, Copper, Hydrogen Types of Mixtures There are two categories of mixtures: Homogeneous Mixtures and Heterogeneous Mixtures Homogenous Mixtures When we add sugar, water and lemon juice together they all uniformly mix with each other. Now it i