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प्रश्न
Explain the following giving an example.
Pure substance
उत्तर
- A pure substance is defined as one that contains only one type of atom or molecule.
- A pure substance has the same colour, taste and texture at any given temperature and pressure and a fixed melting and boiling point under continuous pressure.
- Examples include hydrogen gas, salt chloride, and water.
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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
Write short answer.
What are man-made changes ?
Fill in the blank.
When a candle burns, wax melts. Melting of wax is a ________ change.
State whether the following is physical or chemical changes.
Slaking of lime —
True or false
Is melting of ice a reversible change?
Match the columns.
| Column A | Column B |
| 1. a change which cannot be easily reversed | a. man-made change |
| 2 a change that repeats itself at regular intervals | b. chemical chang |
| 3. a change that is made by humans | c. physical change |
| 4. a change in which the original substance cannot be obtained | d. periodic change |
| 5. a change where no new substance is formed | e. irreversible change |
| f . slow change |
State one instance where water undergoes a physical change and one in which it undergoes a chemical change.
Classify the following as physical or chemical change :
Formation of curd from milk
Fill in the blank.
A change, which alters the composition of a substances, is known as a___________ change.
