Question

a student collected four different samples of river water for an experiment at a specific time of day and a specific location along the river. each sample that was taken had a different volume. the volumes are
sample a: 250 ml
sample b: 500 ml
sample c: 750 ml
sample d: 1,000 ml
the student added a random number of drops of reactant to each of the samples. her results showed inconsistencies compared to what she expected.
what might have caused this?
select all that apply.
□ the time of day that the samples were taken
□ the difference in the volume of water that was sampled
□ the location of sampling
□ the random number of drops of reactant added to each sample

Explanation:

The volume of the sample can affect the reaction outcome as more volume may require more reactant for a consistent result. Adding a random number of reactant drops means there is no controlled variable, leading to inconsistent results. The time of day and location were kept constant, so they are not likely causes.

Answer:

• the difference in the volume of water that was sampled
• the random number of drops of reactant added to each sample