Achemical reaction in which compounds break up into simpler constituents is a reaction.
a. double replacement
b. substitution
c. decomposition
d. combination

C) Decomposition. Double replacement would be AB + CD = AD + BC, substitution is AB + C = CB + A, and combination is A + B = AB

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom