Answer: changed by molecular oxygen
Explanation:
Biologically induced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere.
The answer is D. Optimal
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The statements that are true of heterogeneous mixtures are: they settle out and the proportions of solute to solvent may vary. The correct answer is option A. 1 and 2. Heterogeneous mixtures are considered mixtures wherein the components are not uniform and still retain their properties. Characteristics of heterogeneous mixtures are: the ratio of solute and solvent is not equal, the substances can be separated physically and they still retain their properties even if mixed with another substance.
Answer:
technology has helped make the daily lives of people easer. it has also caused lost of problems such as using up all of the fossil fuels. it has also let to pollution and global warming.
Explanation:
