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प्रश्न
Fill in the blank
Revolution of the earth around the sun is a ________ change.
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उत्तर
Revolution of the earth around the sun is a natural periodic change.
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संबंधित प्रश्न
Tick the most appropriate answer.
5. Photosynthesis requires
- heat energy.
- wind energy
- sunlight.
- sound energy
Write true or false for the statement
A natural change can also be a desirable change
Write true or false for the statement.
Dissolving of solute in a solvent and rusting of iron are both physical changes.
Two chemical substances X and Y combine together to form a product P which contains both X and Y X + Y P
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following statements concerning X, Y and P are correct ?
- P is a compound
- X and Y are compounds
- X and Y are elements
- P has a fixed composition
Classify the following as physical or chemical change :
Formation of curd from milk
Change is the law of nature and occurs in our everyday life, at all times and in all places.
Differentiate between the following change with a suitable example.
Periodic and non-periodic change
State whether the following statement is true or false. If false write the correct statement.
Melting of butter and wax are examples of chemical changes.
What is the difference between dissolution of sugar and burning of sugar ?
Water is known as a universal solvent. Why?
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think rust is different from iron?
