Hormones ! hope i helped :)
Answer:
a.
ZnS(s) + O2(g) → ZnO(s) + SO2(g)
b.
HCl (aq) + Ba(OH)2(aq) → BaCl2(aq) + H2O
So scientist around the world can share there info without having to convert and doing extra work.
Homeostasis is the ability to maintain stable internal conditions B is the answer