A magical or medicinal potion/solution
Each isotope has a unique rate of decay, making them suitable for determining the dates of ancient artifacts. The answer is "rate of decay of the isotope."
The answer is CI because that is the largest
There are different types of indicators for different neutralization reactions. The best indicator for giving a colour change at the equivalence point of a neutralization reaction depending on the pH range of a particular indicator and the equivalence point of the reaction. For instance, the best indicator for a neutralization reaction that involve the titration of NaOH with an acid which result in 9.00 equivalence point is phenolphtalein. This is because the equivalence point which is 9.00 is within the pH range of the indicator, which is between 8.0 to 10.1.