Table listing chemical compounds with their formulas, names, common uses, elemental composition, and atom counts.

Let’s go row by row and fill in the missing parts of the table. We’ll use what we know about chemical formulas, names, common uses, elements, and atom counts.

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Row 1: CH₄ – methane
Already complete. Good example to follow.

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Row 2: H₂S – hydrogen sulfide
- “You have seen this substance before…” → Already given: “Rotten egg smell – flatulence” ✔
- Element names: Hydrogen and Sulfur
- Number of atoms: 2 x H, 1 x S

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Row 3: O₂
- Name: oxygen (it’s a gas we breathe)
- You have seen this substance before…: Breathing air / used in hospitals for patients
- Element names: Oxygen
- Number of atoms: 2 x O

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Row 4: ??? — Fire extinguishers — 1 x C, 2 x O
Formula must be CO₂ (carbon dioxide)
- Name: carbon dioxide
- Element names: Carbon and oxygen
(We already have atom count)

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Row 5: CH₃COOH
This is acetic acid (vinegar!)
- Name: acetic acid (or ethanoic acid)
- You have seen this substance before…: Putting on chips → vinegar! ✔
- Element names: Carbon, Hydrogen, Oxygen
- Count atoms:
- C: 2 (one in CH₃, one in COOH)
- H: 4 (3 in CH₃ + 1 in COOH)
- O: 2 (both in COOH)
→ So: 2 x C, 4 x H, 2 x O

Wait — let’s double-check formula: CH₃COOH = C₂H₄O₂ → yes, correct.

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Row 6: C₁₂H₂₂O₁₁ – sucrose
- You have seen this substance before…: Table sugar ✔
- Element names: Carbon, Hydrogen, Oxygen
- Number of atoms: 12 x C, 22 x H, 11 x O

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Row 7: ??? — Used to bleach hair — 2 x H, 2 x O
That’s hydrogen peroxide → H₂O₂
- Formula: H₂O₂
- Name: hydrogen peroxide
- Element names: Hydrogen and oxygen
(Atom count already given)

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Row 8: C₈H₁₀N₄O₂ – caffeine
- You have seen this substance before…: Coffee, tea, energy drinks
- Element names: Carbon, Hydrogen, Nitrogen, Oxygen
- Number of atoms: 8 x C, 10 x H, 4 x N, 2 x O

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Row 9: C₈H₉NO₂ – paracetamol
- You have seen this substance before…: Painkiller (like Tylenol or Panadol)
- Element names: Carbon, Hydrogen, Nitrogen, Oxygen
- Number of atoms: 8 x C, 9 x H, 1 x N, 2 x O

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Row 10: ??? – copper
Copper is an element, not a compound → symbol is Cu
- Formula: Cu
- You have seen this substance before…: Electrical wires, pennies, statues (like Statue of Liberty)
- Element names: Copper
- Number of atoms: 1 x Cu

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Now let’s compile all answers into the table format as requested.

Final Answer:

| | Formula | Name | You have seen this substance before... | Element names | Number of atoms |
|---|---------------|------------------|-----------------------------------------------|-----------------------------|--------------------------|
| 1 | CH₄ | methane | Gas stoves for cooking | Carbon and hydrogen | 1 x C<br>4 x H |
| 2 | H₂S | hydrogen sulfide | Rotten egg smell – flatulence | Hydrogen and sulfur | 2 x H<br>1 x S |
| 3 | O₂ | oxygen | Breathing air / medical oxygen | Oxygen | 2 x O |
| 4 | CO₂ | carbon dioxide | Fire extinguishers | Carbon and oxygen | 1 x C<br>2 x O |
| 5 | CH₃COOH | acetic acid | Putting on chips | Carbon, hydrogen, oxygen | 2 x C<br>4 x H<br>2 x O |
| 6 | C₁₂H₂₂O₁₁ | sucrose | Table sugar | Carbon, hydrogen, oxygen | 12 x C<br>22 x H<br>11 x O |
| 7 | H₂O₂ | hydrogen peroxide| Used to bleach hair | Hydrogen and oxygen | 2 x H<br>2 x O |
| 8 | C₈H₁₀N₄O₂ | caffeine | Coffee, tea, energy drinks | Carbon, hydrogen, nitrogen, oxygen | 8 x C<br>10 x H<br>4 x N<br>2 x O |
| 9 | C₈H₉NO₂ | paracetamol | Painkiller (Tylenol/Panadol) | Carbon, hydrogen, nitrogen, oxygen | 8 x C<br>9 x H<br>1 x N<br>2 x O |
|10 | Cu | copper | Wires, pennies, statues | Copper | 1 x Cu |