The presence of iron oxides in rocks, formed during a specific time period, can be used as evidence of oxygen in the atmosphere during that time period. question 18 options: true false

True

Explanation:

Iron oxides can only form naturally in the presence of oxygen as shown the formulae below:

2Fe(II) + O2 → 2FeO

4Fe(III) + 3O2 → 2Fe2O3

The presence of naturally occurring iron oxides can, therefore, be a significant indicator of the presence of oxygen in the atmosphere.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.