True. Each contour line on a topographic map represent a certain elevation; the closer they are, the steeper the surface is. All points on a contour line are the same elevation.
An animals life in a desert is to survive, depending on the type of desert though, but I assume the most common desert, the hot/dry desert. Most animals are nocturnal, because it becomes cooler at night, and live underground during the day.
Alright, so that means we have 0.68 mol of the compound
For each 1 mol of the compound, we have 4*1 oxygens (because there are four oxygens in the formula)
Therefore for each 0.68 mol of the compound, we have 4*0.68 moles of oxygen!
