際際滷

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Sreelal Pillai

The document discusses different types of changes that occur in nature and through human activities. It describes natural changes like plants growing and artificial changes like the processing of milk into curd. The document also explains physical changes, where an object's physical properties change but not its chemical makeup, and chemical changes, where the chemical properties and composition change. To demonstrate these concepts, it provides examples of heating a hacksaw blade, which undergoes a physical change, and burning magnesium ribbon, which undergoes a chemical change.

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What all activities take place around every day? In your science diary with the changes happening in your kitchen and surroundings? Are there helpful and harmful ones among then? Are there natural changes or artificial changes? Which are they?........ Changes Natural changes Eg: Bud changes to flower Eg: Milk changes to curd Babies grown up Changes Eg: Milk changes to curd Eg: decay of vegetables Day turns to night Iron resting. Artificial changes Helpful changes Harmful changes
Change is the law of nature. We grow every minutes as our body undergoes a change without which are cannot survive. Students may be aware of various changes taking place in nature. Broadly these changes are two types: Physical & Chemical changes Activity- 1 Hold a used hack- saw blade with a pair of tongs. Keep the tip of the free end. On the flame of a gas stove. Wait for a few minutes. Remove the blade from the flame. Observe the tip once again after some time. The hacksaw blade changed colour on heating and came back to the original colour. Properties such as shape, size, colour and state of a substance are called physical properties. A change in which a substance undergoes a change in its Physical properties is called a physical change.
Activity- 2 Get a small piece of a thin strip or ribbon of magnesium. Clean it up with sand paper. Bring the tip. Near a candle flame. It burns with a brilliant white light. When it is completely burned it leaves behind a powdery ash. A change in which a substance a change in its chemical properties is called a chemical change.
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CONCLUSION Changes is the law of nature. We glow every minutes as our body undergoes a change without which are cannot survive. A change in which a substance undergo a change in its physical properties is called a physical change. A change in which a substance undergo a change in its chemical properties is called a chemical change.

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  • 4. What all activities take place around every day? In your science diary with the changes happening in your kitchen and surroundings? Are there helpful and harmful ones among then? Are there natural changes or artificial changes? Which are they?........ Changes Natural changes Eg: Bud changes to flower Eg: Milk changes to curd Babies grown up Changes Eg: Milk changes to curd Eg: decay of vegetables Day turns to night Iron resting. Artificial changes Helpful changes Harmful changes
  • 5. Change is the law of nature. We grow every minutes as our body undergoes a change without which are cannot survive. Students may be aware of various changes taking place in nature. Broadly these changes are two types: Physical & Chemical changes Activity- 1 Hold a used hack- saw blade with a pair of tongs. Keep the tip of the free end. On the flame of a gas stove. Wait for a few minutes. Remove the blade from the flame. Observe the tip once again after some time. The hacksaw blade changed colour on heating and came back to the original colour. Properties such as shape, size, colour and state of a substance are called physical properties. A change in which a substance undergoes a change in its Physical properties is called a physical change.
  • 6. Activity- 2 Get a small piece of a thin strip or ribbon of magnesium. Clean it up with sand paper. Bring the tip. Near a candle flame. It burns with a brilliant white light. When it is completely burned it leaves behind a powdery ash. A change in which a substance a change in its chemical properties is called a chemical change.
  • 8. CONCLUSION Changes is the law of nature. We glow every minutes as our body undergoes a change without which are cannot survive. A change in which a substance undergo a change in its physical properties is called a physical change. A change in which a substance undergo a change in its chemical properties is called a chemical change.