<h3>
Answer:</h3>

<h3>
General Formulas and Concepts:</h3>
<u>Math</u>
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
<u>Chemistry</u>
<u>Atomic Structure</u>
<u>Stoichiometry</u>
- Using Dimensional Analysis
- Analyzing Reactions RxN
<h3>
Explanation:</h3>
<u>Step 1: Define</u>
[RxN - Balanced] 2C + O₂ → 2CO₂
[Given] 0.25 moles O₂
[Solve] moles CO₂
<u>Step 2: Identify Conversions</u>
[RxN] 1 mol O₂ → 2 mol CO₂
<u>Step 3: Stoichiometry</u>
- [DA] Set up:

- [DA] Multiply/Divide [Cancel out units]:

8.9 g/cm3 since density equals mass/volume or m/v you just divide 89 by 10 to get 8.9
1) H
2) He
3) Li
4) Be
5) B
6) C
7) N
8) O
9) F
10) Ne
11) Na
12) Mg
13) Al
14) Si
15) P
16) S
17) Cl
18) Ar
19) K