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प्रश्न
Give the reason why the following is considered as chemical changes.
An iron nail kept open in the atmosphere rusts.
उत्तर
Rust of iron is a chemical change as iron rust [Fe2O3χ H20] is a brown flaky powder having a different composition from original iron metal, which is an irreversible change.
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संबंधित प्रश्न
Write true or false for the statement.
Deforestation is a man-made change
Solve this crossword by using the clues that follow.
Across
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
6. The process in which a solid directly changes into gaseous state.
Down
1. It is the change that takes place in case of swinging pendulum of a clock.
2. Occurrence of this is a non-periodic change as well as a natural change.
3. It is a physical change
What do you observe when :
lighted match stick is brought near the mouth of the test tube containing hydrogen gas.
Fill in the blank.
When a candle burns, wax melts. Melting of wax is a ________ change.
Fill in the blank.
Growing of a seedling into a plant is _______ change.
State whether the following is physical or chemical changes.
shaping a piece of glass —
Is a change of state of matter – a physical or a chemical change. Give reasons.
Select the chemical changes from the following list of changes
Vaporisation of water into water vapour.
Select the correct answer from the choice given below to complete the sentence
The energy required for completion of a physical change is ______________ when the change is reversed.
Distinguish physical and chemical changes.
