78 and 78. An atom of the element has 78 electrons and 78 protons.
The atomic number is 78, so the atom has 78 protons (+).
If the atom is neutral, it must contain 78 electrons (-).
Whdhrntggmtkasbudubbffjtt
4.5 billion years old
Hope this helps!!!
<u>Answer:</u> The mass of iron (II) oxide that must be used in the reaction is 30.37
<u>Explanation:</u>
The given chemical reaction follows:

By Stoichiometry of the reaction:
When 635 kJ of energy is released, 6 moles of iron (II) oxide is reacted.
So, when 44.7 kJ of energy is released,
of iron (II) oxide is reacted.
Now, calculating the mass of iron (II) oxide by using the equation:

Moles of iron (II) oxide = 0.423 moles
Molar mass of iron (II) oxide = 71.8 g/mol
Putting values in above equation, we get:

Hence, the mass of iron (II) oxide that must be used in the reaction is 30.37