Agalvanic cell with e o cell = 0.30 v can be constructed using an iron electrode in a 1.0 m fe(no3)2 solution, and either a tin electrode in a 1.0 m sn(no3)2 solution, or a chromium electrode in a 1.0 m cr(no3)3 solution even though sn2+/sn and cr3+/cr have different reduction potentials. give the overall balanced reaction for fe-sn cell. do not include the states of matter.

The half reactions are written below.

Explanation:

Oxidation reaction is defined as the reaction in which an atom looses its electrons. The oxidation number of the atom gets increased during this reaction.

Reduction reaction is defined as the reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

We are given a chemical cell which is Fe-Sn cell. The half reaction follows:

Oxidation half reaction:  

Reduction half reaction:  

The substance having highest positive potential will always get reduced and will undergo reduction reaction. Here, zinc will always undergo reduction reaction will get reduced.

Total cell reaction:

Hence, the half reactions are written above.

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.