2. A scientist read an article in a magazine about how air pollution can cause children to develop asthma. Since the article did not come from a peer-reviewed magazine, he doubted the claim,
instead believing that children living in a smog-filled city would not have an increased chance of
developing asthma He wanted to test his own idea, so he formed a hypothesis and planned out
an experiment. The scientist decided to compare 10th graders from three schools in smog-filled
cities to 10th graders from three schools in smog-free rural areas. He found out how many of
these students had asthma and recorded his data in the table below. After looking at the results,
he was amazed at what a big risk factor living in a smog-filled city was after all. (20 points)
a. Identify the steps of the scientific method. (5 points
b. Answer the following questions about the experiment.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.