A 71.0 mL aliquot of a 1.80 M solution is diluted to a total volume of 218 mL. A 109 mL portion of that solution is diluted by adding 113 mL of water. What is the final concentration? Assume the volumes are additive

The final concentration is 0.288 M (approximately)

Explanation:

Using dilution formula:

C1V1 = C2V2

Where C1 is the initial concentration

C2 is the final concentration

V1 is the initial volume

V2 is the final volume

In the first dilution, C1 = 1.8M,

V1 =71mL, V2 = 218mL from the formula C2 = 1.8 ×71/281

=0.5862M

In the second dilution,

C1 = 0.5862M, V1 = 109mL, V2 = 222 mL (109+113)

C2 = 0.5862 × 109 ÷ 222

= 0.288 M (approximately) assuming volume is additive.

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.

i'm assuming that it's c.) red bank..