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Changes Around Us: Physical and Chemical

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Ice melts in a glass. A cut apple turns brown. Are these the same kind of change?

Two changes. Are they the same kind?

This is Chapter 5 in your NCERT book.

Its name is Changes Around Us: Physical and Chemical.

What you will learn

  • Physical change — no new substance is made.
  • Chemical change — a new substance is made.
  • Some changes can be undone. Some cannot. That is a separate question.
  • A burning candle has both kinds of change.
  • Rocks change slowly, over thousands of years.
  • Burning needs fuel, oxygen and heat.
  • A chemical change can be written in words.
  • Some changes help us. Some harm us.

Need a quick catch-up?

These lessons help. Open one if it feels shaky.

  • The same water, three forms (in A Journey through States of Water).
  • Does it dissolve? (in Materials Around Us).
  • Why iron goes orange (in The World of Metals and Non-metals).

Stay safe

Nothing here asks you to light a flame or taste anything. Your teacher may show some tests. Do not try them at home.

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This track

  1. 0 Start here
  2. 1 Fold it, cut it, crumple it
  3. 2 Ice, water and steam are one substance
  4. 3 Dissolving is not disappearing
  5. 4 Some of these will not go back
  6. 5 Checkpoint: changes that make nothing new
  7. 6 A test for something new
  8. 7 Five signs, and what each one is worth
  9. 8 One candle, two changes at once
  10. 9 Two questions, not one
  11. 10 Slow changes in rocks
  12. 11 Checkpoint: new substances and the two questions
  13. 12 Burning needs air
  14. 13 The fire triangle
  15. 14 A change written in words
  16. 15 Useful and harmful changes
  17. 16 Checkpoint: burning, equations and useful changes
  18. 17 The big picture
  19. 18 Track quiz

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