Answer:
Hydrogen and helium compounds.
Explanation:
We know that the solar System was formed around <u>4.6 billion years ago, </u>due to the gravitational collapse of a giant interstellar molecular cloud.
This cloud is a type of interstellar cloud and its density and size permit the formation of molecules, most commonly molecular hydrogen.
Therefore the principal substances were found before planets began to form are hydrogen and helium compounds, besides Rocks, metals, most of them in gaseous form.
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I think the correct answer from the choices listed above is option A. A high frequency wave is a wave with a low level of energy and a high pitch. Frequency is the number of waves passing per second of time. Hope this answers the question.
They communicate their result to the scientific community- so to speak
Answer: A PN-junction diode is formed when a p-type semiconductor is fused to an n-type semiconductor creating a potential barrier voltage across the diode junction
Explanation: hope this helped