Because Air itself is not an element. it is made up by different elements such as Oxygen and nitrogen. since its made up of a mix of different elements, its rather a homogeneous mixture :)
When humans burn fuel/cut down tress, they will increase the level of carbon dioxide within the atmosphere. Tress "inhale" the carbon dioxide within the atmosphere and without them, the excess will still linger. Carbon dioxide is a byproduct of burning fuel thus, it will increase the levels in the atmosphere.
Mass = 5 g
volume = 20 cm³
density = mass / volume
therefore:
D = m / V
D = 5 / 20
D = 0.25 g/cm³
Hi yes bestie just make sure you eat enough so that you can actually build the mussel
