Try to understand all the rules and laws like:
Aufbau Principle
Hund's rule
Pauli exclusion principle...
Then, you should understand the way in which you can fill the electrons in the orbitals!!
This problem is providing some chemical formulas and the number and types of atoms are required according to them; thus, we proceed as follows:
<h3>Chemical formulas:</h3><h3 />
In chemistry, we define chemical formulas as expressions showing the types and number of atoms a substance has. The types of atoms are found across the periodic table and the number is defined by the subscripts appearing in the formula.
a. It should be Fe₂O₃ as iron(III) oxide and in such a case it will have two iron atoms and three oxygen atoms.
b. It is potassium permanganate and it has one atom of both manganese and potassium and four oxygen atoms.
c. It should be CH₄, methane, and in such a case, it will have one carbon atom and four hydrogen atoms.
d. It should be NH₄NO₃, ammonium nitrate, and in such a case it will have two nitrogen atoms, four hydrogen atoms and three oxygen atoms.
Learn more about atoms and chemical formulas: brainly.com/question/5716048
The answer to your question is,
A. Numbers
-Mabel <3
