What are the correct coefficients when this equation is balanced? ___ Sb + __ O2 --> Sb4O6

4 Sb, 3

Explanation:

  On the reactant's side of the equation (the left side), there is one Antimony and one Oxygen gas molecule (). The oxygen gas molecule is made of two atoms, so we actually have 2 oxygens on the left side. On the product's side (the right side), there are 4 antimony atoms, and 6 oxygen atoms. If we were to write it out in a certain way, it would look like this:

__Sb + __ -->

                  1   Sb   4

                  2   O   6

  To balance this equation, those numbers on either side of the elements must equal each other. We can accomplish this with the proper coefficients. If we put a 4 in front of the antimony, it means this:

4 Sb + __ -->

                  4   Sb   4

                  2   O   6

And the antimony is now balanced.

  Now we must balance the oxygen. There are 6 oxygens on the product's side but only 2 on the reactant's side. To fix this, simply multiply the oxygen by 3:

4 Sb + 3 -->

              4   Sb   4

              6   O   6

3 * 2 = 6, so now oxygen is balanced, and the equation is now correct.

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.