Salt water contains n sodium ions (NA ) per cubic meter and n chloride ions (Cl-) per cubic meter. A battery is connected to metal rods that dip into a narrow pipe full of salt water. The cross-sectional area of the pipe is A:

hello your question is incomplete below is the complete question

Salt water contains n sodium ions (Na+) per cubic meter and n chloride ions (Cl−) per cubic meter. A battery is connected to metal rods that dip into a narrow pipe full of salt water. The cross sectional area of the pipe is A. The magnitude of the drift velocity of the sodium ions is VNa​ and the magnitude of the drift velocity of the chloride ions is VCl​.

What is the magnitude of the ammeter reading ?

answer :

| I | = neAVₙₐ  + neAV (Cl-)

Explanation:

Given that there are N sodium ions

Determine the Magnitude of the ammeter reading

| I | = current due to sodium ions + current due to (Cl-) ions

     = neAVₙₐ  + neAV (Cl-)

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.

they vary. it used to be meat, grain, bread, candy, beverages, donuts, and fruits/vegetables. now they added exercise in.