"Worksheet for practicing counting atoms in chemical formulas, focusing on coefficients and subscripts."

Let’s go through each problem step by step. We’re looking for:

- Coefficient: The big number in front of the whole formula (if there’s no number, it means 1).
- Subscript: The small number after an element symbol that tells you how many atoms of that element are in one molecule or unit. If there’s no subscript, it means 1.

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Problem 1: 3MgCl₂

- Coefficient: There’s a “3” in front → 3
- Subscript for Mg: No number after Mg → that means 1
- Subscript for Cl: There’s a “2” after Cl → 2

✔ Matches what’s already filled in — good!

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Problem 2: V₂O₅

- Coefficient: No number in front → that means 1
- Subscript for V: “2” after V → 2
- Subscript for O: “5” after O → 5

✔ Also matches what’s written — correct!

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Problem 3: 4K₂CO₃

- Coefficient: “4” in front → 4
- Subscript for K: “2” after K → 2
- Subscript for C: No number after C → that means 1
- Subscript for O: “3” after O → 3

✔ All match what’s filled in — perfect!

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Problem 4: NaC₂H₃O₂

This is sodium acetate. Let’s break it down:

- Coefficient: No number in front → 1
- Subscript for Na: No number after Na → 1
- Subscript for C: “2” after C → 2
- Subscript for H: “3” after H → 3 ← *Wait! This is missing in the image!*
- Subscript for O: “2” after O → 2 ← *Also missing in the image!*

⚠️ Important: The worksheet only asks for subscripts for Na and C so far — but if we were to complete all, we’d need H and O too. Since the question only shows blanks for Na and C, we’ll just fill those.

But let’s double-check the formula: NaC₂H₃O₂

That means:
- 1 Na atom
- 2 C atoms
- 3 H atoms
- 2 O atoms

So for the blanks given:

- Coefficient: 1
- Subscript for Na: 1
- Subscript for C: 2

✔ These match what’s written.

BUT — notice the worksheet doesn’t ask for H or O here. So unless instructed otherwise, we stop at what’s asked.

However, since this is practice and we want to be thorough, let’s make sure we understand: sometimes formulas like this can be tricky because they group atoms (like O₂ at the end), but here it’s clear: C₂, H₃, O₂.

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Now, let’s verify everything again quickly:

1) 3MgCl₂ → coeff=3, Mg_sub=1, Cl_sub=2 ✔
2) V₂O₅ → coeff=1, V_sub=2, O_sub=5 ✔
3) 4K₂CO₃ → coeff=4, K_sub=2, C_sub=1, O_sub=3 ✔
4) NaC₂H₃O₂ → coeff=1, Na_sub=1, C_sub=2 ✔

All answers provided in the image are correct based on standard chemical notation rules.

Final Answer:
All answers shown in the worksheet are correct as written:
1) coefficient: 3, Mg subscript: 1, Cl subscript: 2
2) coefficient: 1, V subscript: 2, O subscript: 5
3) coefficient: 4, K subscript: 2, C subscript: 1, O subscript: 3
4) coefficient: 1, Na subscript: 1, C subscript: 2