A stone bead and an iron bead are dropped into a cup of water. They both sink to the bottom of the cup. What can be said about these beads?Immersive Reader

Both have densities greater than that of water

Explanation:

The ability of objects to either float or sink in a liquid depends on their relative densities.

If an object is denser than a liquid it will completely sink in it, but if the density of the object is less than that of the liquid, it will sink until the weight of liquid displaced is equal to the weight of the object, then it will finally float in that liquid.

In the case of the stone bead and iron beads dropped into a cup of water, hey both sank to the bottom because they are denser than water.

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.

ill try to . no promises tho.

explanation: