Question

investigation #1: what happens when you add a mentos to a bottle of diet soda ?
type :
benefit: no interference
limitation:

investigation #2: which bottle of soda shows the greatest reaction when mentos is added?
type: comparative
benefit: comparing two or more things
limitation:

investigation #3: how does the amount of mentos affect its reaction with a fixed amount of diet soda?
type: experimental
benefit:
limitation:

terms: research required, researcher bias, variables not controlled, descriptive, hypothesis required, replication, human error, interferes with environment, multiple trials, retest for validity

Explanation:

Investigation #1:

The first investigation is about describing what happens when Mentos is added to diet soda. The "descriptive" type matches as it focuses on observing and describing a phenomenon. For limitations, since it's just a description, variables (like temperature, soda brand, etc.) aren't controlled, so "variables not controlled" is a limitation. Also, it might interfere with the environment (like the soda spilling), so "interferes with environment" could be a limitation too, but the main descriptive - type limitation here is lack of variable control. The type is "descriptive".

This is a comparative investigation. When comparing, there can be researcher bias (the researcher might favor one soda type), human error (in measuring the reaction), and variables not controlled (if other factors like soda volume aren't the same). Also, research might be required to know about different soda properties. But a key limitation for comparative studies is that variables might not be controlled properly, and researcher bias can occur. Another is human error in observing or measuring the reaction.

For an experimental investigation (where we manipulate the amount of Mentos), the benefit is that we can test for validity (by repeating with same conditions) and do multiple trials, and also we can have replication (other researchers can repeat the experiment). The limitation can be human error (in counting Mentos, measuring reaction), researcher bias (favoring a result), or interfering with the environment (more Mentos might cause more mess). Also, variables need to be controlled, but if not, that's a limitation. The benefit: test for validity (or multiple trials, or replication, or hypothesis required as experiments need hypotheses). The limitation: human error (or researcher bias, or interferes with environment)

Answer:

Type: descriptive
Limitation: variables not controlled (or interferes with environment)

Investigation #2: