Grade 6 Science Worksheet: 20 Objective & 10 Subjective Questions on Physical and Chemical Changes

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Instructions

Read each question carefully. For Part A, choose the best answer or determine if the statement is true or false. For Part B, write your answer in a complete sentence, providing explanations where required.

Part A: Objective Questions

Multiple Choice

Circle the letter of the best answer for each question.

  1. Which of the following is an example of a physical change?
    1. Baking a cake
    2. Rusting of an iron nail
    3. Melting an ice cube
    4. Burning wood

  2. Which of the following is an example of a chemical change?
    1. Frying an egg
    2. Tearing a piece of paper
    3. Boiling water
    4. Bending a metal spoon

  3. Which of the following is NOT a common sign of a chemical change?
    1. A change in color
    2. The production of a gas (bubbles)
    3. A change in state (like melting or freezing)
    4. The production of light or heat

  4. Dissolving sugar in a glass of water is an example of a:
    1. Chemical change
    2. Physical change
    3. Nuclear change
    4. Permanent change

  5. What happens to the molecules of a substance during a physical change?
    1. They break apart into new atoms.
    2. They keep their identity but may move around.
    3. They combine with other molecules to form a new substance.
    4. They disappear completely.
      5. ol>
    5. The process of iron rusting requires iron, water, and which gas from the air?
      1. Nitrogen
      2. Carbon Dioxide
      3. Helium
      4. Oxygen

    6. When you bake cookie dough, it turns into a cookie. This is a:
      1. Physical change
      2. Reversible change
      3. Chemical change
      4. Change in shape only

    7. Which of these processes is a physical change?
      1. Digesting a sandwich
      2. Milk turning sour
      3. Chopping firewood
      4. Fireworks exploding

    8. The formation of a precipitate (a solid forming from a liquid solution) is a strong clue that a _________ change has occurred.
      1. physical
      2. chemical
      3. state
      4. temperature

    9. All of the following are physical changes EXCEPT:
      1. Bending a paperclip
      2. Melting candle wax
      3. Burning a candle wick
      4. Breaking a window

    10. A change that can usually be easily reversed is a:
      1. Chemical change
      2. Permanent change
      3. Physical change
      4. New substance

    11. When wood is burned, it produces ash and smoke. This is a:
      1. Physical change
      2. State change
      3. Chemical change
      4. Shape change

    12. Photosynthesis in plants, which creates food (sugar) from light, water, and carbon dioxide, is a:
      1. Physical change
      2. Chemical change
      3. Mechanical change
      4. Phase change

    13. What is the common name for the new substance, iron oxide, that is formed during rusting?
      1. Soot
      2. Ash
      3. Rust
      4. Steel

    14. Mixing sand and iron filings together is a:
      1. Chemical change
      2. Physical change
      3. Irreversible change
      4. Reaction
    True or False

    Read each statement. Write 'T' for True or 'F' for False on the line provided.

    1. ____ A change in size or shape is always a chemical change.
    2. ____ When a new substance is formed, a chemical change has taken place.
    3. ____ Freezing water to make ice is an example of a chemical change.
    4. ____ A change in color is always a definite sign of a chemical change.
    5. ____ A burning match is undergoing a chemical change.

    Part B: Subjective Questions

    Answer the following questions in the space provided. Use complete sentences.

    1. In your own words, what is the main difference between a physical change and a chemical change?

      2. _________________________________________________________________________

      _________________________________________________________________________


    2. You leave your new scooter out in the rain, and a week later you see orange-brown spots on the handlebars. Is this a physical or chemical change? Explain why.

      3. _________________________________________________________________________

      _________________________________________________________________________


    3. List two clues or signs that might tell you a chemical change has happened.

      4. _________________________________________________________________________

      _________________________________________________________________________


    4. When you make a fruit salad, you cut up apples, bananas, and strawberries. Is this a physical or chemical change? Why?

      5. _________________________________________________________________________

      _________________________________________________________________________


    5. A piece of paper is torn into small pieces. Then, one of the small pieces is lit with a match and burns. Describe both the tearing and the burning in terms of physical and chemical changes.

      6. _________________________________________________________________________

      _________________________________________________________________________


    6. Is dissolving salt in water a physical or chemical change? How could you prove it?

      7. _________________________________________________________________________

      _________________________________________________________________________


    7. Give an example of a physical change that would be very difficult to reverse.

      8. _________________________________________________________________________

      _________________________________________________________________________


    8. When you drop a bath bomb into water, it fizzes and releases a scent. What type of change is this, and what clue tells you so?

      9. _________________________________________________________________________

      _________________________________________________________________________


    9. Why is the digestion of food in your stomach considered a chemical change?

      10. _________________________________________________________________________

      _________________________________________________________________________


    10. A candle is lit. The wax near the flame melts and drips down the side. The wick burns away. Identify one physical change and one chemical change that is happening.

      11. _________________________________________________________________________

      _________________________________________________________________________




    Answer Key

    Part A: Objective Questions

    1. C. Melting an ice cube
    2. A. Frying an egg
    3. C. A change in state (like melting or freezing)
    4. B. Physical change
    5. B. They keep their identity but may move around.
    6. D. Oxygen
    7. C. Chemical change
    8. C. Chopping firewood
    9. B. chemical
    10. C. Burning a candle wick
    11. C. Physical change
    12. C. Chemical change
    13. B. Chemical change
    14. C. Rust
    15. B. Physical change
    16. F (False)
    17. T (True)
    18. F (False)
    19. F (False - e.g., adding food coloring is a physical change)
    20. T (True)

    Part B: Subjective Questions (Sample Answers)

    1. The main difference is that in a physical change, the substance is still the same, it has just changed its form or appearance. In a chemical change, a new substance with different properties is created.
    2. This is a chemical change. The orange-brown spots are rust, which is a new substance (iron oxide) formed when the iron in the scooter reacted with oxygen and water. The formation of a new substance and the color change are clues.
    3. Two clues are: production of a gas (bubbles), production of light/heat, an unexpected color change, or the formation of a precipitate. (Any two are acceptable).
    4. This is a physical change. You are only changing the size and shape of the fruit. An apple piece is still an apple, and a strawberry slice is still a strawberry. No new substances were formed.
    5. Tearing the paper is a physical change because you are only changing its size and shape. Burning the paper is a chemical change because the paper turns into new substances like ash and smoke.
    6. It is a physical change. You can prove it by boiling the salt water. The water will evaporate (a physical change), and the salt crystals will be left behind, showing the salt was never destroyed.
    7. An example is shattering a glass into thousands of tiny pieces. While it is still glass (a physical change), it would be practically impossible to put it all back together perfectly. (Other answers like grinding a rock into dust are also correct).
    8. This is a chemical change. The clue is the fizzing, which is the production of a gas (carbon dioxide bubbles). This indicates a chemical reaction is occurring.
    9. Digestion is a chemical change because acids and enzymes in your stomach break down the complex food molecules into simpler new molecules that your body can absorb and use for energy. The original food is changed into new substances.
    10. Physical Change: The wax melts from a solid to a liquid. It is still wax.
      Chemical Change: The wick (and the wax vapor) burns, reacting with oxygen to produce light, heat, soot (carbon), and gases. This is a chemical reaction that creates new substances.
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