What term describes making a series of dilutions where each step reduces the concentration by the same factor?

• A. Serial dilution
• B. Parallel dilution
• C. Stepwise dilution
• D. Incremental dilution

Answer: (A)

This is describing a serial dilution. In a serial dilution, you take a solution and dilute it by a fixed factor at each step, using the previous dilution as the source for the next one. For example, you might transfer 1 mL of the current solution into 9 mL of diluent, giving a 1:10 dilution, then repeat that same step with the new dilution, producing another 1:10 reduction, and so on. The concentrations form a geometric sequence because the same ratio is applied every time, which is exactly what makes it a series of dilutions with equal factors.

This is different from parallel dilutions, which are separate dilutions made independently, or from terms like stepwise or incremental dilutions, which describe sequential work but do not inherently imply a constant dilution factor across every stage. The serial dilution term captures both the sequential nature and the uniform reduction factor.