one part of dalton's atomic theory states: compounds are formed by combinations of atoms from two or more elements. is this statement currently considered to be true or false and why?

The statement is considered to be true

Explanation:

The statement is true because when elements chemically combine, there are interactions between their valence electrons, causing the two elements to be bonded together to form what is known as a compound.

Compounds can only be formed from interactions between two or more elements. examples include:

Hydrogen + Oxygen = H2O (water)

Sodium + Chlorine = NaCl

Note that if atoms of the same element combine, what is formed is a molecule, not a compound. Some atoms usually do this to attain stability. examples include = O2 H2 and  N2. They are oxygen molecule, hydrogen molecule, and nitrogen molecule respectively.

Compounds are only formed when different elements combine to attain electronic stability.

what he said was true

Explanation: i wished that i could have said the same.

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.

lol for the pointsss