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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
Fill in the blank.
Changes that occur in nature are called ........................
Write true or false for the statement.
Dissolving of solute in a solvent and rusting of iron are both physical changes.
Photosynthesis cannot take place at night.
State whether the following is physical or chemical changes.
water cycle in nature —
True or false
Is melting of ice a reversible 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.
When a woolen yarn is knitted to get a sweater, the change can be classified as ____________.
Stretching gold coin into a ring is a ______ change.
Gas exists in three states as solid, liquid, and gas.
Classify the following as physical or chemical properties
Metallic sodium is soft enough to be cut with a knife.
