Ascientist observed changes in the gas pressure of one mole od a grass in a sealed chamber with a fixed volume. to identify the source of the change, the scientist should check for variations in the
a. air pressure
b. molecular formula
c. temperature of the chamber
d. isotopes of the gas

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: