Classify each of the following substances:

CO2, BF3, CO, O2, CH4

a) Lewis Acid
b) Lewis Base
c) Can act as either a Lewis Acid or Lewis Base
d) Neither a Lewis Acid or Lewis Base

Explanation:

Carbon dioxide is a polar molecule whose positive center is on the carbon atom: This positive center is able to attract (and accept) the lone electron pairs present on the oxide ion (O2-). carbon dioxide is acts as a Lewis acid

A Lewis acid can accept a pair of electrons from a Lewis base. The boron in BF3 is electron poor and has an empty orbital, so it can accept a pair of electrons, making it a Lewis acid. A Lewis acid is defined as an electron-pair acceptor.

In CO molecule, there is a lone pair on both carbon and oxygen. The substance which can donate an electron pair are called Lewis base. It is clear that CO molecule can donate an electron pair and hence, it is a Lewis base. Also, CO can be BOTH a Lewis acid and base.

Oxygen is a Lewis base (that too a weak one), not a Lewis acid. REASON: It has lone pair of electrons, which can be donated to electron-deficient species (Lewis acids).

Methane is Neither a Lewis Acid or Lewis Base.

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.