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प्रश्न
Compare the energy changes involved during a physical and a chemical change.
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उत्तर
- Physical change: No gain or loss of energy during physical change.
The energy required for completion of a physical change is released when the change is reversed. - Chemical change: Energy is either absorbed or evolved during the chemical change.
The energy in the form of light, percussion (pressure), or generally heat energy is required for a chemical change.
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Cutting of trees
Fill in the blank.
When a candle burns, wax melts. Melting of wax is a ________ change.
State the Differences Between a Physical Change and a Chemical Change.
Classify the following as a physical or a chemical change.
Melting of wax
Given reason:
Cutting of a cloth piece is a physical change, though it cannot be reversed.
Give three reasons why melting of wax, is considered a physical change while burning of a candle, a chemical change.
State whether the following statement is true or false. If false write the correct statement.
Melting of butter and wax are examples of chemical changes.
State which of the following terms connected with change of state of matter i.e.
(a) Melting
(b) Vaporisation
(c) Condensation
(d) Freezing
pertain to –
- Conversion of a liquid into a vapour or gas.
- Conversion of a liquid into a solid.
- Conversion of a solid into a liquid on heating.
Give a reason why – Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
Give two examples for the following case:
Physical changes which are reversible
