If the density of a substance is d=2.1g/cm^3 what is the mass of 20.0mL of this substance

Explanation:

density = mass (g)/ volume (cm3)

    2.1 =   mass / 20 cm3

     mass = 42 g

be attention that each 1 ml =1cm3                    

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: