In 1885, Johann Balmer, a numerologist, derived the following relation for the wavelength of lines in the visible
spectrum of hydrogen:
Wavelength = 364.6 n²/(n^2 - 4)
where wavelength is in nanometers and n is an integer that can be
3, 4, 5, Show that this relation follows from the Bohr
equation and Equation 5.2. Note that, for the Balmer series, the electron is returning to the n = 2 level.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

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.