Changes Around Us | Class 7 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 2 min read
Changes Around Us – this guide gives you a concise, exam-ready overview of Changes Around Us from Class 7 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
Effect of Heating
Heating causes various changes in materials depending on their nature. It can cause physical changes such as melting, evaporation, and expansion, or chemical changes such as burning and decomposition. When a solid is heated, it may melt to form a liquid, and further heating can cause evaporation to gas. Heating can also cause expansion in solids, liquids, and gases due to increased kinetic energy of particles. In some cases, heating causes chemical changes; for example, burning wood or decomposing calcium carbonate to calcium oxide and carbon dioxide. The effect of heating depends on the material and the temperature applied. Understanding the effect of heating is important in daily life and industrial processes such as cooking, metalworking, and manufacturing.
📊 Diagram: Diagrams show melting of ice on heating, burning of wood producing flames and ash, and decomposition of calcium carbonate in a test tube.
🧪 Activity: Activity: Heating a test tube containing calcium carbonate and observing the formation of calcium oxide and gas.
🔗 Connection: This section connects to the next, which explains the effect of cooling on materials.
Frequently asked questions
Which of the following is an example of a physical change?
Melting of ice
What is a chemical change? Give one example from daily life.
A chemical change is a change in which one or more new substances with different properties are formed. For example, burning of wood is a chemical change because it produces ash, carbon dioxide, and water vapor which are different from wood.
Which of the following changes is irreversible?
Burning of paper
Explain why melting of ice is considered a physical change.
Melting of ice is a physical change because it involves a change in state from solid to liquid without changing the chemical composition of water. The water molecules remain the same, only their arrangement changes.
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