An atom that has 19 protons, 21 neutrons, and 18 electrons has a mass of ? *

a chair, a bed, and a toothbrush

explanation:

i was told this before by a teacher, so yeah

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

i hope this : )

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex