Chlorophyll a is one of the green pigments found in plants. chlorophyll a has the molecular formula c55h72mgn4o5. how many atoms are in this molecule?

There are 55 carbon 72 hydrogens 1 magnesium 4 nitrogen and 5 oxygen 
so that would be 55+72+1+4+5

and that is 137 

Yes she is correct. the answer is completely correct

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