Answer:
The answer to your question is c. H2O
Step-by-step explanation:
a. CaCO3 ----> Calcium Carbonate is obviously not a binary compound because it contains more than two elements.
b. CuSO4 ----> CuSO4 stands for copper(II) sulfate. Sulfate is the polyatomic ion SO4 -2.
c. H2O ----> Binary molecular compounds are composed of only two elements. Examples are H2O, NO, SF6 etc.
d. Pb(NO3)2 ----> Lead(II) nitrate is an inorganic compound with the chemical formula Pb(NO3)2.
I hope this helps and have a great day!