Which of these nine alkanes are gases at room temperature (20°c)

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:

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.