cbse board std 7 science

NCERT Solutions Std 7 Science Physical and Chemical Changes

Physical and Chemical Changes Exercise:   1). Classify the changes involved in the following processes as physical or chemical changes: (a) Photosynthesis (b) Dissolving sugar in water (c) Burning of coal (d) Melting of wax (e) Beating aluminium to make aluminium foil (f ) Digestion of food Physical Changes Chemical Changes Dissolving sugar in water …

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NCERT Solutions Std 7 Science Acids, Bases and Salts

Acids, Bases and Salts Exercise: 1). State differences between acids and bases. Acids Bases 1. Acids are substances that contain hydrogen ion.   1. Bases are substances that contain hydroxyl ion. 2. Acid turns blue litmus red.   2. Base turns red litmus blue. 3. Acids are sour to taste.   3. Bases are bitter …

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NCERT Solutions Std 7 Science Fibre to Fabric

Fibre To Fabric Exercise: 1). You must be familiar with the following nursery rhymes: (i) ‘Baa baa black sheep, have you any wool.’ (ii) ‘Mary had a little lamb, whose fleece was white as snow.’ Answer the following: (a) Which parts of the black sheep have wool?  Ans: Fleece – the hairy skin of the …

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NCERT Solutions Std 7 Science Nutrition in Animals

Nutrition in Animals Exercise: 1). Fill in the blanks: (a) The main steps of nutrition in humans are ingestion, digestion, absorption, assimilation and egestion. (b) The largest gland in the human body is the liver. (c) The stomach releases hydrochloric acid and digestive juices which act on food. (d) The inner wall of the small …

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NCERT Solutions Std 7 Science Nutrition in Plants

Nutrition in Plants Exercise: 1). Why do organisms take food?      Organisms need food for growth and development. Food also provides energy.   2). Distinguish between a parasite and a saprotroph. Parasite Saprotroph 1. A parasite is an organism that takes the food from the living thing on which it survives. 1. An organism that …

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