Use the periodic table to choose the element that matches each description.
halogen:
group iia:
nonreactive:
alkali metal:

The periodic table is arranged in periods and in groups. Periods tell us the energy level of these elements and the groups tell more about the characteristics.

Elements found in the same groups have similar characteristics. Elements in the same group are arranged vertically, or they are found in the same column.  

The halogen group is also known as Group VIIA or Group 17. It is the second to the last column of the periodic table. They are highly reactive and are non-metals. They have 7 valence electrons. The elements that fall in this group are:

Group IIA is also known as the Alkaline Earth Metals. They are reactive and form ionic bonds with non-metals. They have 2 valence electrons. This group is found in the 2nd column from the left side of the periodic table. The elements that fall in this group are:

The most non-reactive elements are found in the last column on the right side of the periodic table. This group is called Group VIIIA or Group 18, collectively known as Noble gases. These elements are not reactive because they have a filled outer energy levels, or they have complete 8 valence electrons (except Helium, which has 2 but it completes the shell). The elements that fall under this group are:

Alkali metals are found in the 1st column from the left in the periodic table (except for Hydrogen). This group is also called Group 1 or Group IA. They are reactive and often form salts. The elements that fall under this group are:

halogen: Iodine

group IIA: Magnesium

nonreactive: Argon

alkali metal: Potassium

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.

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.