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प्रश्न
Define a chemical change. Give two examples of the above changes.
उत्तर
A permanent change in which new substances are formed whose composition and properties are completely different from those of the original
substances.
Chemical change:
(i) Burning of wood.
(ii) Breathing.
संबंधित प्रश्न
Fill in the blank
change in which the substance can be brought back to its original state is called a ............... change.
Write short answer.
What are man-made changes ?
Write short answer.
Sublimation is classified as a physical change. Why ?
Classify the following changes as physical or chemical:-boiling
State whether the following is physical or chemical changes.
respiration in living beings —
Tick (√) the correct alternative from the choice given for the following statement
Which one of the following is volatile in nature ?
True or false
In a physical change no net energy change is involved.
A physical change is temporary. Explain.
State the various conditions that favour the process of evaporation.
Which of the following are physical changes and which are chemical changes ?
Freezing of water
Fill in the blank.
A change, which alters the composition of a substances, is known as a___________ change.
Give four difference between physical and chemical changes.
Ammonium chloride is also a sublimable solid. Give a reason why the sublimation of ammonium chloride involves a physical and a chemical change.
Give reasons why – separation of mixtures e.g. iron from a mixture of iron and sulphur is a physical change, but heating a mixture of iron and sulphur is considered a chemical change.
Fill in the blank with the correct word of the statement given below:
Sublimation of iodine is an example of _________ change.
Give a reason why
Freezing of water is a reversible change while burning of a candle – an irreversible change.
Is a change of state of matter – a physical or a chemical change. Give reasons.
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.
Stretching gold coin into a ring is a ______ change.
Classify the following changes as physical and chemical changes
A rough piece of wood is sanded and polished resulting in change in texture, Rusting of a iron nail, Painting the grill, Bending a paper clip, Pounding silver into thin plate, Rolling the chappathi dough into thin wire, Occurrence of day and night, eruption of volcano, burning of matchstick, dosa from the batter, blinking of eyelids, occurrence of a thunderstorm, rotation of the earth, formation of eclipses.
| Sr. No. | Physical changes | Chemical changes |
| 1. | ||
| 2. |
