D. Has a uniform composition and is only able to be separated by chemical means.
<span>Na (sodium) is highly electropositive. Its has 1 electron in its outermost orbit which is transferred to an electronegative atom to form an ionic bond.
It only needs to get rid of one valence electron to take part in a reaction. That's how it's highly reactive.</span>
C) S
Because of the trends of electronegativity. Increases across a period and decreases down a group.