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:
Making a fruit salad with raw fruits
Chemical changes are accompanied by changes in energy.
Name a chemical change which takes place in presence of:
Fill in the blank
Chemical change occurs as a result of __________ between two substances.
State whether the following is physical or chemical changes.
(energy produced) dissolving sugar in water —
Tick the most appropriate answer.
Physical changes are
Make a list of different types of changes with example.
What is a physical change ? Give two examples of physical changes.
Define a chemical change. Give two examples of the above changes.
Change is the law of nature and occurs in our everyday life, at all times and in all places. Differentiate between the following change with a suitable example.
Desirable and undesirable change.
Change is the law of nature and occurs in our everyday life, at all times and in all places.
Differentiate between the following change with a suitable example.
Natural and man-made change.
Select the correct answer from the choice given below to complete the sentence
The dissolution of lead nitrate in water is deemed as a _________ change.
A change in which matter undergoes a change but the total mass of the substance is unaltered is a ______ change.
Give the reason why the following is considered as chemical changes.
Copper carbonate on heat gives copper oxide and carbon dioxide.
In a solution of salt in water, water is the solute
Wood to sawdust:______:: Wood to Ash: Chemical change
Assertion: The explosion of fire cracker is a physical change.
Reason: A physical change is a reversible change.
Fill in the blanks in the following statements using the words given in the box.
| rusted, colourful, substance, chemical, physical, reversible, iron oxide, object |
- Making sugar solution is a ______ change.
- A physical change is generally ______.
- Grinding of wheat grain changes its size. It is a ______ change.
- Iron benches kept in lawns and gardens get ______. It is a ______ change because a new ______ is formed.
The change of state of a substance from solid to liquid and liquid to gas is ______.
Keeping a stone in sunlight for few hours is ______.
