How does an atom become charged? -How does an atom get a positive charge?
-How does an atom get a negative charge?
-Can an atom get a charge with a change of particles in
the nucleus? Explain, please.

An atom becomes charged when there is an unequal amount of positive and negative particles in the nucleus.

An atom gets a positive charge when there is an increase in protons or a decrease in electrons, such that there are more protons than electrons in the nucleus.

An atom gets a negative charge when there is an increase in electrons or a decrease in protons, such that there are more electrons than protons in the nucleus.

An atom can get a charge with a change of particles in the nucleus if that change results in an uneven number of protons and electrons.

Explanation:

Because protons are positively charged particles and electrons are negatively charged particles, a neutral atom has an equal amount of protons and electrons, so that the opposite charges of the particles cancel each other out.

However, if there is an unequal amount of protons or electrons in the nucleus, the charge of the particles will no longer be canceled out, and the atom as a whole will take on a positive or negative charge.

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.