The Curiosity rover found sulfur compounds in rocks and carbon in organic compounds like propane, butene, benzene, toluene and thiophene.
It detected methane, not in soil samples, but in the Martian atmosphere.
It did not discover helium in underground pockets. The hole it can drill is only 5 cm deep.
Answer:
A molecule is a group of two or more atoms held together by chemical bonds. A compound is a substance which is formed by two or more different types of elements which are united chemically in a fixed proportion. All molecules are not compounds.
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