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Activity Discussion Science & Technology Science class 7th Reply To: Science class 7th

  • Gautam

    June 21, 2023 at 11:45 am
    Not Helpful
    1. Photosynthesis: Chemical change. Photosynthesis is a complex biochemical process in which plants convert sunlight, water, and carbon dioxide into glucose and oxygen. It involves the synthesis of organic compounds, which is a chemical transformation.

    2. Melting of wax: Physical change. Melting of wax involves the solid wax transitioning into a liquid state when exposed to heat. It is a physical change as the chemical composition of the wax remains the same, only its physical state changes.

    3. Dissolving of salt in water: Physical change. Dissolving of salt in water is a physical change as it involves the salt crystals dispersing and becoming uniformly mixed with water. While the salt ions separate and disperse throughout the water, there is no change in the chemical composition of the salt or water molecules.

    4. Digestion of food: Chemical change. Digestion is a series of chemical processes that break down complex food molecules into simpler substances that can be absorbed and utilized by the body. Enzymes and acids in the digestive system facilitate the chemical breakdown of food components, resulting in the release of nutrients.

    5. Burning of coal: Chemical change. Burning of coal involves a chemical reaction known as combustion. It is a chemical change because coal combines with oxygen from the air to produce carbon dioxide, water vapor, and releases energy in the form of heat and light. The chemical composition of coal changes during this process.

    It’s important to note that the classification of changes as physical or chemical may depend on the level of detail considered and the context in which they occur.

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