Which of the following characteristics do all of the outer planets have in common? a. they lack moons. b. they are small and dense. c. they have liquid cores. d. they are mostly made up of hydrogen and helium.

The answer is D. They are mostly made up of hydrogen and helium.

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8