A county has 800,000 people in an area of 200,000 acres. The county has one large population center, while the rest of the county has an equal distribution of individuals. What is the population density of this county?

explanation:

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.