Why is oxygen spelt o2

it's a diatomic molecule–which is why it is O₂.

Explanation:

Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. Only a handful of elements on the periodic table are diatomic such as nitrogen, hydrogen, fluorine, chlorine, bromine, and iodine.

when atmosphere interacts with biosphere they focuses on on the sources and sinks of green house gases (ghgs) air pollutants, particular matters, water and energy between the earth's surface and the atmosphere. the biosphere affects the climate. the atmosphere and biosphere are in constant interaction with each other, and all living things rely on gases in the atmosphere for life. organisms such as animals take in oxygen gas form the atmosphere to use in every cell of their body for smooth functioning of daily routine exercises.

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.