Radical chlorination of pentane is a poor way to prepare 1-chloropentane, but radical chlorination of neopentane, (ch3)4c, is a good way to prepare neopentyl chloride, (ch3)3cch2cl.
why?

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:

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.