Out of 2.00 50 ml of water is added to 30 ml of a 0.50 m salt solution. what is the new concentration? (to write your answer using scientific notation use 1.0e-1 instead of 1.0 x 10-1)

The concentration of the new solution will be 0.31 M

Explanation:

The number of moles per liter of the solution is 0.50 mol. Then, in 50 ml there will be:

50 ml · (0.50 mol / 1000 ml) = 0.025 mol.

If we add 30 ml and assuming that the solution is an ideal solution, the final volume will be 80 ml.

Then, 0.025 mol will be present in 80 ml solution. In 1 l there will be:

1000 ml · (0.025 mol / 80 ml) = 0.31 mol.

The concentration of the new solution will be 0.31 M.

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.

the answers would be

the first one and the second one