<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>Stoichiometry</u>
- Using Dimensional Analysis
<h3>
Explanation:</h3>
<u>Step 1: Define</u>
[RxN - Balanced] 2Al₂O₃ → 4Al + 3O₂
[Given] 20 mol Al₂O₃
<u>Step 2: Identify Conversions</u>
[RxN] 2 mol Al₂O₃ → 4 mol Al
<u>Step 3: Stoich</u>
- [DA] Set up:

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

<u>Step 4:Check</u>
<em>Follow sig fig rules and round. We are given 1 sig fig.</em>
Since our final answer already has 1 sig fig, there is no need to round.
Answer: The coefficient is 3.645
The exponent is 1
There are 4 significant digits
The rightmost significant figure is 5
Explanation:
Scientific notation is defined as the representation of expressing the numbers that are too big or too small and are represented in the decimal form with one digit before the decimal point times 10 raise to the power.
For example : 5000 is written as 
According to avogadro's law, 1 mole of every gas contains avogadro's number
of particles, occupy 22.4 L at STP and weighs equal to its molecular mass.
131.29 g of Xe occupy = 22.4 L at STP.
Thus 213.62 g of
occupy =
at STP.
Scientific notation = 
The coefficient is 3.645
The exponent is 1
There are 4 significant digits
The rightmost significant figure is 5
C because, its products is heavier than each of its reactants
Answer:
Explanation:
Reaction given
6 H⁺ + 2 MnO₄⁻ + 5 (COOH)₂ = 10CO₂ +8H₂O + 2 Mn⁺²
Oxidation number of Mn in MnO₄⁻
= x - 4 x 2 = -1
x = 8 -1
+ 7
Oxidation no of Mn in Mn⁺² = +2
So its oxidation no is decreased from + 7 to + 2 . Hence it is reduced.