What is the purpose of a stock solution?

• A. To have a concentrated source that can be diluted to achieve various working concentrations.
• B. To be used as is for all experiments.
• C. To be unused due to instability.
• D. To be discarded after one use.

Answer: (A)

The main idea is to have a concentrated source that can be diluted to achieve various working concentrations. A stock solution is prepared at a known, high concentration and stored so you can quickly generate any required final concentration by adding the right amount of diluent. This approach lets you make multiple working solutions from one reference point, improves accuracy through standardized dilutions, and saves time by avoiding preparing each concentration from scratch. Using the stock as is would limit flexibility, since different experiments often need different concentrations. Stocks are not inherently unusable or discarded after a single use; they’re designed to be reused (often aliquoted to avoid repeated handling) under appropriate storage conditions, with fresh preparation or substitution when stability limits are reached.