Advertisements
Advertisements
प्रश्न
A burning candle shows both physical and chemical changes. Explain ?
Burning of a candle is both a physical and chemical change.
Advertisements
उत्तर १
A burning candle produces wax vapours which solidify and form wax again is physical change. At the same time wax on burning produces water vapours and carbondioxide which escape into the atmosphere which are new substances with new properties. It is a chemical change.
Hence burning of candle shows both physical and chemcial changes.
उत्तर २
When a candle is lighted, some of the solid wax first melts and turns into liquid, then it turns into vapours to produce a flame. New substances CO2 and H2O vapours are formed along with the evolution of light and heat energy. This shows a chemical change. When some of the molten wax drops to the floor, it again solidifies. Which shows a physical change. Thus the melting of candle wax is a physical change and the production of CO2 and H2O represents chemical change.
संबंधित प्रश्न
Classify the following as chemical or physical change:
Cutting of trees
Classify the following as chemical or physical change:
Dissolving common salt in water.
Fill in the blank
Revolution of the earth around the sun is a ________ change.
State whether the following is physical or chemical changes.
water cycle in nature —
Write true or false
Earthquake is a desirable change.
Photosynthesis cannot take place at night.
What are man-made changes ?
Classify the Following as a Physical Or a Chemical Change.
Curdling of Milk
Give three reasons why melting of wax, is considered a physical change while burning of a candle, a chemical change.
Fill in the blank with the appropriate word of the statement given below:
If a change is permanent and irreversible it is considered a _________ change.
Change is the law of nature which occurs in everyday life.
State when a substance [i.e. matter] undergoes a kind of change.
Compare the energy changes involved during a physical and a chemical change.
Name the following.
The product of the chemical change in keeping a polished iron nail exposed to the atmosphere.
Digestion of food is a physical 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. |
What is the difference between dissolution of sugar and burning of sugar ?
Higher order Thinking question
Boiling of water is a physical change; but boiling of egg is a chemical change. Why?
Classify the following as physical or chemical properties
Metallic sodium is soft enough to be cut with a knife.
