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Acids Bases and Salts Notes || Class 10 Chapter 2 Science ||



Chapter 2, Class 10 ACIDS, BASES AND SALTS Acids 1.Those substances which has sour (खट्टा) taste, is called acids. 2.The chemical nature of such substances is acidic. 3.The acids present in plant materials and animals are called organic acids. 4.Organic acids (or naturally occurring acids) are weak acids. 5.E.g. Curd, lemon juice, orange juice and vinegar (सिरका) taste sour, it means acidic in nature.
Important name of the Organic acids 1.Acetic acid contains in vinegar 2.Formic acid (Methanoic acid) in Ant’s sting (डंकमारना), Nettle sting 3.Citric acid – Citrus fruits such as oranges, lemons, etc. 4.Lactic acid in Curd (दही) 5.Oxalic acid in Spinach (पालक), tomatoes 6.Ascorbic acid (Vitamin C) in Amla, Citrus fruits 7.Tartaric acid in Tamarind (
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Is Matter around us pure Notes || Class 9 Chapter 2 Science ||



Chapter – 2 IS MATTER AROUND US PURE? 1.If we observe some sugar and some soil (mitti) placed on two different sheets of paper with a magnifying glass, we will find that the colour, shape and size of all the particles of sugar are the same, but the soil contains particles of different colours, shapes and sizes. 2.E.g. the soil contains clay (चिकनीमिट्टी) particles, some grass particles and even some dead insects (कीड़ा) etc. 3.Now, sugar which contains particles of only one kind is called a pure substance whereas soil which contains particles of different kinds is called an impure substance (or mixture). 4.From this we conclude that all the matter around us is not pure.
Matter 1.Anything which occupies space & has mass is called matter. OR 2.Anything which has volume & mass is called matter. OR 3.Any Object which is made up of atoms is called matter. 4.The matter around us is of two types: pure and impure (mixtures) subst…
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Microorganisms Friend and Foe Notes || Class 8 Chapter 2 Science ||




Chapter – 2, Science MICROORGANISMS: FRIEND AND FOE 1.Microorganisms/microbes are very small which cannot be seen with the help of eyes. 2.We use microscope or magnifying glass to see them. 3.E.g. fungus that grows on bread
Classification of Microorganisms 1.It is classified into four major groups 2.Bacteria, fungi, protozoa and algae 3.Viruses are other kind of microorganisms. 4.They are explained below – Bacteria 1.Bacteria are very small, single celled micro-organisms which have cell walls but do not have an organised nucleus & other structure 2.These are found everywhere like in air, soil, water, every surface around us, on our bodies or inside our body. 3.Two common examples are Lactobacillus & Rhizobium 4.Some are useful & help in making foods (like curd (दही