12. Which property of a mixture could be used to tell the difference between a container of salt water and a container of distilled water?
A. A mixture is not uniform.
B. A mixture contains more than one identifiable particle.
C. A mixture looks different than the pure substances from which it is made.
D. A mixture has different melting and boiling points than the pure substances
from which it is made.

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

i think is conclusions.i think so

the answer is c.the valence of the atoms combine .