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Question
Fill in the blank
Heat is ________ by a gas during the process of condensation.
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Solution
Heat is released by a gas during the process of condensation.
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RELATED QUESTIONS
Changes in which only ______ properties of a substance change are called physical changes.
Classify the following changes as physical or chemical:-boiling
Fill in the blank.
When a candle burns, wax melts. Melting of wax is a ________ change.
Photosynthesis cannot take place at night.
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.
Which of the following are physical changes and which are chemical changes ?
Rusting of iron
Classify the following as a physical or a chemical change.
Manufacture of salt from sea water
Potassium chloride is added to water and stirred. A salt solution is obtained, which is then boiled, leaving behind a residue.
- Is the above change physical or chemical?
- Name the residue which remains behind after the salt solution is boiled.
- Is the change reversible or not reversible?
- Are the composition and properties of the original substance altered?
- Give a reason why the above experimentation would not be possible if calcium carbonate was taken in place of potassium chloride.
Filling up a balloon with hot air is a _______ change.
Analogy:
Melting of ice: Physical change.
Popping of popcorn: ______.
