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प्रश्न
Explain the term – ‘sublimation’. Is sublimation of naphthalene – a physical or a chemical change. Give reasons.
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उत्तर
It is the conversion of a solid – directly into gaseous (vapour) state and on cooling directly back to solid-state – without changing into a liquid state.
It involves a change of state-and hence it is a physical change.
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संबंधित प्रश्न
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
Classify the following changes as physical or chemical:- melting of a solid (wax)
Define physical change. Give two examples for the above changes.
State the various conditions that favour the process of evaporation.
Classify the Following as a Physical Or a Chemical Change.
Formation of Clouds
Fill in the blank with the correct word of the statement given below:
Sublimation of iodine is an example of _________ change.
State which of the following pertain to – chemical changes.
- Substance retains its identity.
- The change is permanent.
- No new substance is formed.
- Is easily reversible.
- Produces one or more new substances by a change in its composition.
- The change is temporary.
- The composition and properties of the original substance are not altered.
Select the chemical changes from the following list of changes
Preparation of carbon dioxide from calcium carbonate & dilute hydrochloric acid.
Distinguish physical and chemical changes.
Higher order Thinking question
Boiling of water is a physical change; but boiling of egg is a chemical change. Why?
