Classify the matter in these diagrams as elements, compounds, or mixtures for a Grade 9 IGCSE Chemistry worksheet.

Let's solve this IGCSE Chemistry worksheet on the Classification of Matter, step by step.

We are given 12 diagrams showing different arrangements of atoms (represented by black and white circles). We must classify each diagram into one of the following categories:

- A. Elements – made of only one type of atom (can be diatomic or polyatomic, but all atoms are the same).
- B. Compounds – molecules made of two or more *different* types of atoms chemically bonded together in a fixed ratio.
- C. Mixtures of elements – two or more different elements present as separate atoms or molecules, not chemically bonded.
- D. Mixtures of compounds – two or more different compounds present, not chemically bonded to each other.
- E. Mixtures of elements and compounds – both elements and compounds present together.

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Let’s analyze each diagram:

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1)
- All molecules are the same: each has one black atom and two white atoms → consistent molecular structure.
- This is a compound (two different atoms bonded together).
- Answer: B

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2)
- There are black atoms and white atoms scattered individually.
- No bonding between them; they're just mixed.
- Two different elements present.
- Answer: C (Mixture of elements)

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3)
- Two types of molecules:
- One molecule has three black atoms (possibly O₃ or similar)
- Another has two white atoms (like O₂)
- Both are elements (each made of one type of atom).
- So, mixture of two different elemental molecules.
- Answer: C (Mixtures of elements)

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4)
- All molecules are the same: one central black atom with three white atoms → same compound.
- Uniform composition.
- Answer: B (Compound)

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5)
- Only black atoms present, all individual (not bonded).
- But they are all the same type → pure element.
- Even if individual atoms, it's still an element.
- Answer: A (Element)

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6)
- All molecules are identical: four black atoms per molecule, arranged in a specific way.
- Same compound throughout.
- Answer: B (Compound)

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7)
- All molecules are two white atoms bonded together → diatomic molecule.
- All same → pure substance.
- Since all atoms are the same type, it's an element.
- Answer: A (Element)

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8)
- Contains:
- Individual black atoms
- Individual white atoms
- Molecules of one black + one white (bonded)
- So we have:
- Elements (free black and white atoms)
- A compound (black-white bonded)
- Therefore, mixture of elements and compounds
- Answer: E

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9)
- Contains:
- Individual black atoms
- Diatomic white molecules (O₂-like)
- Two different elements present as separate entities.
- Answer: C (Mixtures of elements)

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10)
- Two types of molecules:
- One is two white atoms (diatomic element)
- Other is one black + two white atoms (compound)
- So: element + compound
- Answer: E (Mixtures of elements and compounds)

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11)
- All molecules are identical: four black atoms in a square pattern.
- Uniform → pure substance.
- All atoms are the same → element (even though it's polyatomic).
- Example: P₄ (white phosphorus).
- Answer: A (Element)

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12)
- Molecules are identical: one black and one white atom bonded.
- All same → compound.
- Answer: B (Compound)

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Final Answers:

1) B
2) C
3) C
4) B
5) A
6) B
7) A
8) E
9) C
10) E
11) A
12) B

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Summary Table:

| # | Answer |
|---|--------|
| 1 | B |
| 2 | C |
| 3 | C |
| 4 | B |
| 5 | A |
| 6 | B |
| 7 | A |
| 8 | E |
| 9 | C |
| 10| E |
| 11| A |
| 12| B |

✔ These classifications follow the rules of matter classification based on atomic composition and bonding.

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