Answer:
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Explanation:
Roughly 96 percent of the mass of the human body is made up of just four elements: oxygen, carbon, hydrogen and nitrogen, with a lot of that in the form of water. The remaining 4 percent is a sparse sampling of the periodic table of elements
Hope this helps :)
Answer:

Explanation:
The molecular mass of a monomer unit is:
C₂H₃Cl = 2×12.01 + 3×1.008 + 35.45 = 24.02 + 3.024 + 35.45 = 62.494 u
For 1565 units,

The best answer is the first option. A bike rusting is an example of a chemical change since rusting is a chemical reaction. New substances are formed from this reaction. On the other hand, other choices given are just physical changes because only the shape or the physical form of the substances are being changed.
I think the correct answer from the choices listed above is option B. The following reaction does not proceed to form a product: H2O + Au---> no reaction because gold has a lower activity than hydrogen and cannot replace it. Hope this answers the question.