Consider two samples of carbon. one is a sample of one mole of carbon atoms obtained from the environment (i. e. isotopes are present according to their natural abundance), and the other is a sample of one mole of carbon-12 atoms (i. e. isotopically pure). which sample has a higher mass, or are they both the same mass? justify your answer, either with words or mathematically

The sample obtained from the environment has a higher mass

Explanation:

A simple way to put the answer is that the element carbon -as found in nature- has a molar mass of 12.0107 g/mol, because there are a few isotopes of 14C and 13C; and the molar mass is an expression of the isotopes' natural abundance.

So 1 mole of carbon obtained from the environment would weigh 12.0107 g, while a sample of isotopically pure carbon would weigh 12.0000 g.

a polar bond is formed when electrons are shared unevenly between atoms

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.