Are u sure this is the right option? Well, antimony can be decomposed. Including octane.
Dihydrogen oxide is the right answer. Dihydrogen oxide is just 2 hydrogen and 1 oxygen which is H2O or water.
Carbon, helium, and sodium are monoatomic elements.
Hydrogen, iodine, and oxygen are diatomic elements.
C. mass is protons and neutrons. Both are in the nucleus
