I think the correct answer from the choices listed above is option D. the substances cobalt and barium chloride will not react since cobalt os less active than barium so it does not have enough energy to displace barium in the compound. Hope this answers the question.
Im sure that the answer is C, correct me if im wrong.
Answer:
SiS2, silicone disulfide, is a linear, nonpolar compound.
Answer:
: conjugate acid of 
: conjugate base of 
: conjugate base of
: conjugate acid of
Explanation:
According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.
Here in forward reaction is accepting a proton, thus it is considered as a base and after accepting a proton, it forms which is a conjugate acid.
And is losing a proton, thus it is considered as an acid and after loosing a proton, it forms which is a conjugate base.
Similarly in the backward reaction, is loosing a proton, thus it is considered as a acid and after loosing a proton, it forms which is a conjugate base.
And is accepting a proton, thus it is considered as a base and after accepting a proton, it forms 
which is a conjugate acid.
Compounds often differ from elements.
