To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 5.0-L bulb, then filled it with the gas at 1.30 atm and 20.0 ∘C and weighed it again. The difference in mass was 7.5 g . Identify 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: