Advertisements
Advertisements
प्रश्न
Explain the following giving an example.
Pure substance
Advertisements
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.
APPEARS IN
संबंधित प्रश्न
Classify the following as chemical or physical change:
Melting of butter in a pan
Explain why burning of wood and cutting it into small piece are considered as two different types of changes.
Choose the most appropriate answer.
Rising and setting of the sun at a given place is a
Tick the most appropriate answer.
3. Physical changes are
- permanent.
- periodic,
- temporary
- irreversible.
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.
heating a mixture of iron filings and sulphur—
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.
Select the correct answer from the choice given below to complete the sentence
The energy required for completion of a physical change is ______________ when the change is reversed.
Give the reason why the following is considered as chemical changes.
A piece of magnesium strip is dropped into a beaker containing dilute hydrochloric acid.
Physical Change: Boiling::Chemical Change: ______.
