<u>Answer:</u>
<em>Hydrogen and ozone are both examples of trace gases.
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<u>Explanation:</u>
Trace gases are present in minor quantities in the <em>earth’s atmosphere and all the gases except nitrogen, oxygen and argon </em>which make up the major portion of earth’s atmosphere are considered trace gases.
The respective percentages of nitrogen, oxygen and argon in the atmosphere are<em> 78.1%, 20.9% and 0.934%.</em> The process that produce trace gases is called source and the process that removes trace gas from the <em>atmosphere is called sink.
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<em>Some other examples of trace gases are carbon dioxide, neon, helium etc.
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Well the <span>blood returns from the cardiac tissues to the right atrium because
the blood goes through the tricuspid</span> valve and into the right ventricle then the right ventricle makes the blood go to the lungs and thats where the oxygen is at then the blood goes through organs and tissues then gets to the heart through the veins and a vein named the vena cave has the blood return to the right atrium.
Asexual reproduction involves one parent and produces offspring that are genetically identical to each other and to the parent. Sexual reproduction involves two parents and produces offspring that are genetically unique.
Answer: C by breaking down rock in to small pieces
Explanation: