Rank from high to lowest distance

1km, 100m, 50mm, 1cm, 5million nm, 1mm, 1Mm

Convert all quantities to meters

*******PLEASE EXPLAIN HOW YOU GOT THE ANSWER.********

1.) Rank the following charge/distance combinations from lowest energy to highest energy. Your answer should be a four letter "word" made up of the letters a, b, c and d. For example, if you think the order is a (lowest energy), then b, then c, then d (highest energy), you should enter the "word" abcd in the answer box. Note, the word has no spaces or commas.

a) A -3 charge and a +2 charge separated by 3 units of distance

b) A +2 charge and a +2 charge separated by 4 units of distance

c) A -3 charge and a -2 charge separated by 4 units of distance

d) A +2 charge and a -4 charge separated by 3 units of distance

(**I tried bcad but it's not right. Could someone please explain the steps for this problem please)

2.) Which transition in a hydrogen atom would emit the photon of greatest frequency?

n = 35 to n = 2

n = 6 to n = 2

n = 12 to n = 6

n = 1 to n = 4

n = 2 to n = 9

n = 3 to n = 1

3.) Which transition in a hydrogen atom would absorb the photon of greatest frequency?

n = 35 to n = 2

n = 6 to n = 2

n = 12 to n = 6

n = 1 to n = 4

n = 2 to n = 9

n = 3 to n = 1

4.) Rank the following charge/distance combinations from lowest energy to highest energy. Your answer should be a four letter "word" made up of the letters a, b, c and d. For example, if you think the order is a (lowest energy), then b, then c, then d (highest energy), you should enter the "word" abcd in the answer box. Note, the word has no spaces or commas.

a) A +2 charge and a -2 charge separated by 3 units of distance
b) A -3 charge and a -1 charge separated by 3 units of distance
c) A +1 charge and a +1 charge separated by 2 units of distance
d) A -1 charge and a +2 charge separated by 3 units of distance

5.)Which of the following points could be concluded or determined from Thomson's cathode ray experiment?
Check all the boxes that apply. (There may be anywhere from zero to five correct statements.) This question is graded "all or nothing", no partial credit.

-cathode rays were negatively charged

-cathode rays were particles, not light waves

-the numerical mass of the cathode rays

-the numerical charge of the cathode rays

-the charge to mass ratio of the cathode rays