Our understanding of the atom has changed over time. which idea that was once accepted is now considered scientifically inaccurate?
a. the nucleus is the center of the atom.
b. an atom is solid material.
c. electrons have a negative charge.
d. electrons are arranged in layers.

Which sentences describe point source pollution? in this type of pollution, the source of the pollution is single and easily identifiable. when runoff water from the melting of snow mixes with debris, it creates pollution. the runoff water, mixed with pollutants, reaches large areas with disastrous effects. alternatively, when a wastewater treatment plant releases harmful chemicals into a stream, the chemicals pollute the stream water because they are not treated for safety.

Which of the following characteristics of earth's relationship to the sun explains the existence of earth's seasons? choose all that apply. earth has a satellite called the moon, which rotates around earth. earth spins on its axis, completing one rotation each day. earth's axis always points in the same direction relative to the stars. earth's axis is tilted relative to its orbital plane. earth orbits around the sun, completing one orbit each year.

Awave is propagating from left to right in a medium. the particles in the medium are also vibrating from left to right. what kind of wave does this describe? a. longitudinal wave b. transverse wave c. mechanical wave d. electromagnetic wave