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प्रश्न
Give a reason why – Rusting of iron is a chemical change but, the magnetization of iron is a physical change.
उत्तर
Rusting of iron is a chemical change as composition changes, the reddish-brown flaky powder is formed with new properties and is irreversible, permanent change but magnetization of iron is temporary and reversible change with no change in composition is a physical change.
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संबंधित प्रश्न
What role does energy play in initiating a chemical change ?
Tick the most appropriate answer.
Physical changes are
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.
Explain the term – ‘sublimation’. Is sublimation of naphthalene – a physical or a chemical change. Give reasons.
State whether the following statement is true or false. If false write the correct statement.
Melting of ice is an exothermic, irreversible chemical change.
State which of the following pertain to – chemical changes.
(a) Substance retains its identity
(b) The change is permanent
(c) No new substance is formed
(d) Is easily reversible
(e) Produces one or more new substances by a change in its composition
(f) The change is temporary
(g) The composition and properties of the original substance are not altered.
Give four reasons why the burning of a magnesium ribbon in the air is considered a chemical change.
Select the chemical changes from the following list of changes
Butter turning rancid
Physical Change: Boiling::Chemical Change: ______.
Natural changes which take place in nature on their own, are beyond the control of human being.
