There are four accepted fundamental forces or interactions undefined by scientists: gravitational, electromagnetic, strong nuclear,
and weak nuclear. Which choice is an example of the electromagnetic force?
Protons of similar charges are bound together and stabilized within an
atom's nucleus
It is responsible for nuclear beta decay and other similar decay processes
involving fundamental particles
This is the attractive force between matter; between two things that have
mass
Electrons bind with nucleus of an atom, due to the presence of protons

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

answer///terminator or twilight zone;

false

explanation: