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प्रश्न
What do you observe when :
lighted match stick is brought near the mouth of the test tube containing hydrogen gas.
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उत्तर
We observe that hydrogen bums at the mouth of test tube with blue flame and pop sound is heard. It is chemical change.
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Melting of butter in a pan
Write short answer.
What are man-made changes ?
True or false
Is melting of ice a reversible change?
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
Give reasons why – separation of mixtures e.g. iron from a mixture of iron and sulphur is a physical change, but heating a mixture of iron and sulphur is considered a chemical change.
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
Give a reason why – Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
Stretching gold coin into a ring is a ______ change.
Which of the following is a physical change?
Adding sugar to milk is a physical change.
