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प्रश्न
What are man-made changes ?
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उत्तर
Man-made changes are those that occur because of human activities e.g. changing the direction of flow of a river by building a dam.
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संबंधित प्रश्न
Explain why burning of wood and cutting it into small piece are considered as two different types of changes.
Write true or false for the statement.
Deforestation is a man-made change
Classify the following changes as physical or chemical: curdling of milk
True or false
In a physical change no net energy change is involved.
Fill in the blank
Heat is ________ by a gas during the process of condensation.
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
Give four difference between physical and chemical changes.
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.
Natural and man-made change.
State the observations seen, when milk in a dish is kept aside for a few hours or more. Is the change which occurs – a physical change or a chemical change. Give reasons.
Mention some of the different conditions needed for chemical changes to occur.
