What is the purpose of stirring a solution while it is being heated? Select one: To slow down any reactions that occur in the solution To encourage sudden boiling in the solution To prevent the solute from dissolving into solution To help evenly distribute heat throughout the solution

To help evenly distribute heat throughout the solution

Explanation:

The purpose of stirring a solution while being heated would be to evenly distribute heat throughout the solution.

When a vessel containing a solution is heated, the molecules at the lower portion of the vessel get heated first before heat graduate radiates around the entire solution. Stirring the solution will ensure that the process of heat distribution around the entire solution is quickened.

Stirring a solution while heating does not slow down the reactions that might occur in the solution, does not encourage sudden boiling of the solution, and neither does it prevent solute from dissolving into the solution.

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.