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प्रश्न
What is a chemical change ? Give two examples of chemical changes.
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उत्तर
Chemical change: These changes occur when a substance combines with another to form a new substance. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.
Examples:
- Rusting of iron
- Burning of paper
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Melting of butter in a pan
Write short answer.
Give two examples of periodic changes
Tick (√) the correct alternative from the choice given for the following statement
A pop sound is heard when a lighted match stick is brought near the mouth of a jar. This indicates the release of gas.
Tick the most appropriate answer.
Photosynthesis requires
Photosynthesis cannot take place at night.
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
Fill in the blank with the correct word of the statement given below:
Sublimation of iodine is an example of _________ change.
Select the chemical changes from the following list of changes
Vaporisation of water into water vapour.
Select the chemical changes from the following list of changes
Breaking of glass
State whether the following statement is true or false:
Anaerobic bacteria digest animal waste and produce biogas.
