The formula to calculate population density is
a. land area number of populations
b. number of populations land area
c. number of organisms in a region land area
d. land area number of organisms in a region

The correct answer is - b. number of populations land area.

The density of the population is very simple to be calculated. We only need two information's, the number of the population, and the land area where that population lives. Than we divide the number of the population with the land area and we get the result of the density of the population.

Number of population / land area = population density.

For example:

652,008 / 13,404 km² = 48,64/km²

because the two particles have an equal charge, the charges will cancel out and give the atom an overall charge of 0. so, if at atom has 35 protons in the nucleus, we could expect it to have 35 electrons orbiting that nucleus.