NCERT Science Class 7 Chapter 6: Physical & Chemical Changes | NSO | Science Olympiad

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Pure crystals of salt can be obtained by crystallization.
Take about 100 ml of water in a beaker
Add a few drops of sulphuric acid into water and heat the water
When its start boiling at copper sulphate powder added as a saturated solution is obtained.
Now, filter the solution
After sometimes, we can see it prepare shiny crystals of copper sulphate

Chemical Changes
Rusting of iron , Photosynthesis, Respiration, digestion , Ripening of fruits, fermentation
Foul smell of rotting of food; burning of firecrackers
A change in which one or more new substances are formed is called a chemical change. A chemical change is also called a chemical reaction. burning of any substance is a chemical change. Burning is always accompanied by production of heat.
Heat, light or any other radiation (ultraviolet, for example) may be given off or absorbed.
Sound may be produced.
A change in smell may take place or a new smell may be given off.
A colour change may take place .
A gas may be formed.

Types of Changes, ncert class 7, examrace ncert, ncert by dr manishika jain, Based on composition, based on time interval, based on reversibility, based on speed, Experiment of magnesium oxide with water #NSO #NSTSE #Olympiad #NCERT #VVM #examrace #upsc #ugcnet