The formula for density is Mass/Volume,
so the first point on the left the density is 1 g/cm3
the second point in the middle has a density of 1.2 g/cm3
the third point at the top right has a density of 1.6 g/cm3
the last point in the bottom right has a density of 0.083 g/cm3
When atoms react, they tend to achieve an outer shell having eight electrons. Many of the representative elements (sodium and chlorine for instance) follow this rule when they form ions. In the ionic case they achieve the noble gas shell configuration by either a gain or loss of electrons.
Charles and Francis Darwin concluded from their experiments on phototropism by grass seedlings that the part of the seedling that detects the direction of light is the "tip of the coleoptile."
Steepness of a slope (C) is one characteristic of topographic maps.
"The more closely spaced the contour lines, the steeper the slope. You can find out exactly how steep the slope of the area you are interested in by subtracting the lowest elevation from the highest, and dividing the result by the horizontal distance."