Composition variable a, element
b. mixture
c. substance
d. compound
e. matter

c. Substance

Explanation:

A composition variable is an intensive property that indicates the relative amount of a particular species or substance in a phase.

is b the anwer is b

Explanation:

because mixture is a composition variable

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

answer seismograph;