Let’s go step by step to figure out which phrases are examples of
physical changes.
Remember: A physical change means the substance looks different (maybe size, shape, or state), but it’s still the same stuff inside. No new chemical is made.
We’ll look at each phrase and ask: “Is this just a change in form? Or did something new get created?”
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1.
ice melts → Ice turns into water. Still H₂O. Just changed from solid to liquid.
✔ Physical change
2.
glass breaking → Glass shatters into pieces. Still glass. Just smaller pieces.
✔ Physical change
3.
bicycle metal rusting → Rust is a new substance (iron oxide). Chemical reaction happened.
✘ Not physical
4.
bread rising → Yeast makes gas bubbles — that’s a chemical reaction. Bread becomes spongy because of new gases.
✘ Not physical
5.
dissolve salt in water → Salt mixes with water, but you can evaporate the water and get salt back. No new substance.
✔ Physical change
6.
boiling water → Water turns to steam. Still H₂O. Just gas now.
✔ Physical change
7.
frying an egg → Egg white turns solid and changes color. That’s proteins changing chemically.
✘ Not physical
8.
baking a cake → Ingredients react (like baking soda + acid) to make CO₂ and new textures/flavors. New substances formed.
✘ Not physical
9.
milk that has soured → Bacteria turn lactose into lactic acid. Sour taste = new chemical.
✘ Not physical
10.
whipped egg whites → You’re just trapping air in them. They puff up, but it’s still egg white.
✔ Physical change
11.
erosion → Rocks break down into sand or soil due to wind/water. The rock material doesn’t become a new chemical — just smaller bits.
✔ Physical change
12.
folding a piece of paper → Paper bends. Still paper.
✔ Physical change
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So the physical changes are:
✔ ice melts
✔ glass breaking
✔ dissolve salt in water
✔ boiling water
✔ whipped egg whites
✔ erosion
✔ folding a piece of paper
Now, pick any two and describe how they changed.
Example 1:
Ice melts
→ It was hard and cold (solid), then turned into wet water (liquid). Same molecules, just moved around more.
Example 2:
Folding a piece of paper
→ The paper bent and got creases, but it’s still paper. You didn’t burn it or tear it — just changed its shape.
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Final Answer:
Physical changes: ice melts, glass breaking, dissolve salt in water, boiling water, whipped egg whites, erosion, folding a piece of paper.
Two examples described:
- Ice melts: Changed from solid to liquid, but still water.
- Folding a piece of paper: Changed shape, but still paper.
Parent Tip: Review the logic above to help your child master the concept of physical worksheet.
