Answer:
Thus, as both an amphoteric compound and the most common liquid on Earth, it follows that water is both the most common acid as well as the most common base on planet Earth
Yeah what the other person said ^
Dilution formula:
mv = MV
where one side is concentration × volume BEFORE dilution and the other side is concentration × volume AFTER dilution.
(100mL) × (12 M) = (500mL) × (X)
(1200 M·mL) = (500mL) × (X)
(1200 M·mL) / (500mL) = X
2.4 M = X