Question

What is a serial dilution and why might you want to use it?

Answer 1

Serial dilution is starting with a stock solution, then diluting it, for example, 10 times. If we dilute the first dilution 10 times, we get a second dilution which is 100 times more dilute than the stock solution. We can continue to dilute the last dilution and achieve a final dilution of a million times more dilute than the stock solution.
It would be difficult in terms of flask sizes and pipette sizes available to achieve dilution by a large factor in one step.

Answer 2

this is something like the answer should be

Answer 3

why might we use it??

Answer 4

You have a hint on that in my original answer:
"It would be difficult in terms of flask sizes and pipette sizes available to achieve dilution by a large factor in one step." That means that using the serial dilution method we can prepare very dilute solutions in a precise and convenient way.