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प्रश्न
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
उत्तर
- When a candle burns, the melting of wax is a physical change and the burning of the candle is a chemical change. When the wax melts, only its physical properties change.
- Hence, it is a physical change. When a candle burns, its chemical properties and composition change, the melted wax turns into carbon dioxide and other substances and it cannot be obtained in its original form.
- It is a chemical change. Hence, when a candle burns, both physical and chemical changes take place.
Example:
When coal is broken into pieces and burned, both physical and chemical changes occur. Breaking coal into pieces is a physical change. The properties of coal do not change in this. Burning of coal is a chemical change. Due to burning, the chemical properties of coal change and new substances are formed.
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संबंधित प्रश्न
Name a chemical change which takes place in presence of:
State whether the following is physical or chemical changes.
glowing of a bulb -
State whether the following is physical or chemical changes.
growing of a piglet into a pig —
Make a list of different types of changes with example.
Two chemical substances X and Y combine together to form a product P which contains both X and Y X + Y P
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following statements concerning X, Y and P are correct ?
- P is a compound
- X and Y are compounds
- X and Y are elements
- P has a fixed composition
Classify the following as physical or chemical change :
Growth of a plant
Which of the following are physical changes ?
- melting of iron metal
- rusting of iron metal
- bending of an iron rod
- drawing a wire of iron metal
Give a reason why – Rusting of iron is a chemical change but, the magnetization of iron is a physical change.
Give the reason why the following is considered as chemical changes.
Copper carbonate on heat gives copper oxide and carbon dioxide.
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 |
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