Calculate the number of molecules present in 0.750 mol of mgo.

The answer to that would be magnesium

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

C. 1s22s22p63s23p43d104s24p5

What do you need with it’s not a question your just stating what it says