Question

an experiment was designed to measure the effect of sulfur dioxide emissions from a power plant on the ph of rain falling downwind of the plant. in this experiment, the average ph of rainwater upwind from the plant would be considered
○ a model.
○ the hypothesis.
○ a variable.
○ the control.

question 7
1 pts
which of these best describes a scientific model?
○ a small version of a large object
○ a way of explaining a complex concept
○ the most recent version of a theory

Explanation:

First Question (about the experiment with sulfur dioxide and rain pH)

• A model is a representation, not relevant here.
• A hypothesis is a prediction, not the pH measurement.
• A variable is a factor that changes, but the upwind pH is kept constant for comparison.
• The control in an experiment is the group or measurement used as a standard for comparison (to see the effect of the independent variable, here sulfur dioxide emissions). The upwind rain (no sulfur dioxide influence from the plant) is the control to compare with downwind rain.

• A scientific model is a simplified representation (can be conceptual, mathematical, physical) to explain complex concepts/phenomena. A "small version of a large object" is too narrow (only physical scale models, but models can be non - physical like mathematical models). "The most recent version of a theory" is incorrect as models and theories are distinct (theories are broader, models are specific explanations). So "a way of explaining a complex concept" fits.

Answer:

the control.

Second Question (about scientific model, though options are partially visible)

Assuming the visible options are something like (common options for scientific model):

1. a small version of a large object (incorrect, as models aren't just physical scale models)
2. a way of explaining a complex concept (correct, scientific models simplify/explain complex phenomena)
3. the most recent version of a theory (incorrect, models and theories are different, models explain, theories are well - supported explanations)