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प्रश्न
Explain the following giving an example.
Pure substance
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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
Write true or false for the statement
A natural change can also be a desirable change
Write true or false for the statement
Decomposition of leaves is a fast change.
True or false
Is melting of ice a reversible change?
True or false
Dissolving of a solid in liquid is a physical change.
Change is the law of nature and occurs in our everyday life, at all times and in all places.
Differentiate between the following change with a suitable example.
Periodic and non-periodic change
Change is the law of nature and occurs in our everyday life, at all times and in all places.
Differentiate between the following change with a suitable example.
Slow and fast change.
State the observations seen, when milk in a dish is kept aside for a few hours or more. Is the change which occurs – a physical change or a chemical change. Give reasons.
Name the following:
The type of change physical or chemical involved – ‘when a substance undergoes a change in state, colour or size’.
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.
Stretching gold coin into a ring is a ______ change.
