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C. The final substance in beaker A is a pure substance while in Beaker B is a mixture

Explanation:

A pure substance is a substance that contains a constant and definite proportion of a single substance. Elements and compounds are the two known pure substances while mixtures are substances of different compositions mixed together.

In this question, two beakers; A and B are said to contain different substances. Beaker A contains elemental sulfur (S) that forms a yellow powder while beaker B contains sand and water. From the explanation above, the final substance in beaker A is a pure substance (element) while in beaker B is a mixture of sand and water.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

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