Educational worksheet on physical and chemical properties and changes, including definitions and identification exercises.

Let’s go through each part of the worksheet carefully and check whether the answers marked are correct or not. We’ll use the definitions given at the top:

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Physical Property (P):
- Observed with senses
- Determined without destroying matter

Chemical Property (C):
- Indicates how a substance reacts with something else
- Matter changes into a new substance after reaction

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First Section: Identify as Chemical (C) or Physical (P) Property

1. blue color → P ✔ (color is observed with senses, no change in substance)
2. density → P ✔ (measured without changing the substance)
3. flammability (burns) → C ✔ (involves reacting with oxygen to make new substances)
4. solubility (dissolves) → ✘ Should be P — dissolving doesn’t create a new substance; it’s a physical change. Sugar in water is still sugar and water.
→ *Correction: This should be P, not C.*
5. reacts with acid → C ✔ (reaction creates new substances)
6. supports combustion → C ✔ (means it helps other things burn — chemical behavior)
7. sour taste → P ✔ (taste is sensed, doesn’t destroy matter)
8. melting point → ✘ Should be P — melting point is a physical property; you observe when it melts, no new substance formed yet.
→ *Correction: This should be P, not C.*
9. reacts with water → C ✔ (chemical reaction occurs)
10. hardness → P ✔ (physical trait, measured without changing substance)
11. boiling point → ✘ Should be P — like melting point, it’s a physical property. Boiling turns liquid to gas but same substance.
→ *Correction: This should be P, not C.*
12. luster → P ✔ (shininess — seen with eyes)
13. odor → P ✔ (smell — sensed without changing substance)
14. reacts with air → C ✔ (like rusting or oxidation — makes new stuff)

→ So errors here: #4, #8, #11 should be P, not C.

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Second Section: Identify as Physical (P) or Chemical (C) Change

Definitions:
- Physical Change: size/shape/state change, NO new substance
- Chemical Change: new substance formed, properties change

1. NaCl dissolves in water → ✘ Should be P — dissolving salt is physical; you can evaporate water and get salt back.
→ *Correction: P, not C*

2. Ag tarnishes → C ✔ (silver reacts with sulfur in air to form black silver sulfide — new substance)

3. An apple is cut → P ✔ (just shape changed)

4. Heat changes H₂O to steam → P ✔ (state change only)

5. Baking soda reacts to vinegar → C ✔ (produces CO₂ gas — new substance)

6. Fe rusts → C ✔ (iron + oxygen → iron oxide — new substance)

7. Alcohol evaporates → P ✔ (liquid to gas — same substance)

8. Ice melts → P ✔ (solid to liquid — same substance)

9. Milk sours → C ✔ (bacteria turn lactose to lactic acid — new substance)

10. Sugar dissolves in water → ✘ Should be P — same as salt; no new substance
→ *Correction: P, not C*

11. Wood rots → C ✔ (decomposition by microbes — new substances formed)

12. Pancakes cook → C ✔ (heat causes browning, proteins denature — irreversible, new substances)

13. Grass grows → ✘ Should be C — growth involves photosynthesis, making new molecules (glucose, etc.) from CO₂ and water. It’s a biological chemical process.
→ *Correction: C, not P*

14. A tire is inflated → P ✔ (air pumped in — no chemical change)

15. Food is digested → C ✔ (enzymes break down food into different molecules — new substances)

16. Paper towel absorbs water → P ✔ (water soaks in — no chemical reaction)

→ Errors here: #1, #10, #13

#1 and #10 should be P (dissolving is physical).
#13 should be C (growth involves chemical reactions).

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Part A Table: Physical and Chemical Changes

We’ll go row by row:

1. Ice cube → puddle → gone (evaporated) → All state changes → P ✔ Correct

2. Two chemicals mixed → gas produced → New substance → C ✔ Correct

3. Bicycle rusts → color change due to rust (iron oxide) → C ✔ Correct

4. Solid crushed to powder → just size/shape → P ✔ Correct

5. Two substances mixed → light produced → Usually means chemical reaction (like glow sticks) → C ✔ Correct

6. Ice melts AND reacts with sodium → Melting is physical, BUT reacting with sodium is chemical (makes hydrogen gas and NaOH) → Since it says “and reacts”, overall it’s C ✔ Correct

7. Mixing salt and pepper → Just mixing, no reaction → P ✔ Correct

8. Chocolate syrup dissolved in milk → Dissolving = physical → P ✔ Correct

9. Marshmallow toasted over campfire → Burning/charring = chemical change → C ✔ Correct

10. Marshmallow cut in half → Just shape → P ✔ Correct

→ All answers in Part A table are CORRECT!

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## Summary of Corrections Needed:

First Section (Properties):

- #4 solubility → should be P
- #8 melting point → should be P
- #11 boiling point → should be P

Second Section (Changes):

- #1 NaCl dissolves → should be P
- #10 Sugar dissolves → should be P
- #13 Grass grows → should be C

All others are correct.

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Final Answer:
The following items were incorrectly labeled and need correction:

In "Identify as chemical (C) or physical (P) property":
- #4 solubility → change from C to P
- #8 melting point → change from C to P
- #11 boiling point → change from C to P

In "Identify as physical (P) or chemical (C) changes":
- #1 NaCl dissolves → change from C to P
- #10 Sugar dissolves → change from C to P
- #13 Grass grows → change from P to C

All other answers on the worksheet are correct.