Compound A exist in equilibrium with its tautomeric form, compound B. An IR spectrum of a mixture of A and B exhibits four signals in the region 1600-1850 cm^-1. These signals appear at 1620, 1660, 1720 nd 1740 cm^-1. A. Identify the source for each of these four signals and provide a justification for the location of the signal at 1660 cm^-1
B. For most simple ketones, the concentration of the enol tautomer is almost negligible at equilibrium. However, in this case, the concentration of B is significant. Provide a justification for this observation.
C. The IR spectrum of compound C lacks a signal at 1720 cm^-1. Draw the tautomer of C and then determine which tautomeric form predominates at equilibrium.

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.