A3B8 + C2 ---> AC2 + B2C

1. What is the balanced equation for the combustion reaction?

A₃B₈ + 5C₂ –> 3AC₂ + 4B₂C

Explanation:

A₃B₈ + C₂ –> AC₂ + B₂C

The equation can be balance as illustrated below:

A₃B₈ + C₂ –> AC₂ + B₂C

There are 3 atoms of A on the left side and 1 atom on the right side. It can be balance by writing 3 before AC₂ as shown below:

A₃B₈ + C₂ –> 3AC₂ + B₂C

There are 8 atoms of B on the left side and 2 atoms on the right side. It can be balance by writing 4 before B₂C as shown below:

A₃B₈ + C₂ –> 3AC₂ + 4B₂C

There are 2 atoms of C on the left side and a total of 10 atoms on the right side. It can be balance by writing 5 before C₂ as shown below:

A₃B₈ + 5C₂ –> 3AC₂ + 4B₂C

Now, the equation is balanced.

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.

a:

by the combination of an unlimited number of elements