In a chemical change A. materials retain their properties.
B. materials change their properties.
C. new materials do not form.
D. new materials formed are always in liquid form.

B. materials change their properties.

Explanation:

In a chemical change, materials often change their properties because a re-arrangement of atoms takes place.

A chemical change is one in which new kind of matter is formed.

It is always accompanied by energy changes.

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.

that's it!

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