Grade 6 Naming Molecular Compounds Worksheets 2024 - Free Printable

Let's solve each problem step by step using the rules provided in the worksheet.

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Rules Recap:

1. Organic compounds contain carbon (C). Most inorganic compounds do not contain carbon, except CO₂, which is inorganic.
2. Carbohydrates: C:H:O ratio = 1:2:1.
3. Lipids: C:H:O ratio is much greater than 1:2:1 (more carbon and hydrogen relative to oxygen).
4. Amino acids: Contain an amino group (NH₂ or N–H) and a carboxyl group (COOH).
5. Alkanes: Contain only carbon and hydrogen (e.g., CH₄, C₂H₆).

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Now let’s analyze each compound:

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1. Structure:

```
H H H OH H H
| | | | | |
H - C - C - C - C - C - C = O
| | | | | |
OH OH OH H OH H
```

This is a sugar molecule with multiple –OH groups and a carbonyl (C=O) at the end.

- Contains carbon, hydrogen, and oxygen → organic.
- Check C:H:O ratio:
- Count atoms:
- C: 6
- H: 12 (each CH₂ or CH has H; total H = 12)
- O: 6 (5 –OH + 1 carbonyl)
- Ratio: C:H:O = 6:12:6 = 1:2:1 → matches carbohydrate.

✔ Answer:
- Organic
- Carbohydrate

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2. CO₂ (Carbon Dioxide)

- Contains carbon and oxygen.
- But according to Rule 1: CO₂ is an exception — it is inorganic.

✔ Answer:
- Inorganic
- None of these

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3. C₁₂H₂₂O₁₁

- Contains carbon, hydrogen, oxygen → likely organic.
- Check ratio: C:H:O = 12:22:11
- Simplify: divide by 11 → 1.09:2:1 → close to 1:2:1, but not exact.
- Actually, this is sucrose (table sugar), a disaccharide.
- The formula for sucrose is C₁₂H₂₂O₁₁, and it's a carbohydrate.

Note: While the ratio is slightly off from 1:2:1 due to water loss during formation, it's still considered a carbohydrate.

✔ Answer:
- Organic
- Carbohydrate

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4. Structure:

```
H H O
| | ║
H - N - C - C - OH
| |
H - C - H
|
H
```

Let’s simplify this structure:

- Central carbon attached to:
- NH₂ group (N–H₂) → amino group
- COOH group (carbonyl and OH) → carboxyl group
- A side chain: –CH₃ (methyl group)

This is glycine, the simplest amino acid.

✔ Answer:
- Organic
- Protein / amino acid

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5. Mg(OH)₂

- Magnesium hydroxide.
- Contains Mg, O, H → no carbon.
- So, inorganic (by Rule 1).
- Not a carbohydrate, lipid, protein, or alkane.

✔ Answer:
- Inorganic
- None of these

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6. CH₄ (Methane)

- Only carbon and hydrogen → matches Rule 5.
- Alkane (simplest hydrocarbon).

✔ Answer:
- Organic
- Alkane

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✔ Final Answers:

1.
Organic
Carbohydrate

2.
Inorganic
None of these

3.
Organic
Carbohydrate

4.
Organic
Protein / amino acid

5.
Inorganic
None of these

6.
Organic
Alkane

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