How can the number of atoms of an individual element be determined by using a chemical formula?
a. dividing the atomic mass by number of atoms
b. using the subscript after each element
c. multiplying the number of atoms by their masses
d. adding all of the subscripts together after the reaction is complete.

The number of atoms of an individual element be determined by using a chemical formula is adding all of the subscripts together after the reaction is complete. The answer is letter D. The key in the balancing of chemical reaction is to make sure that you got the exact chemical formula of the substance that is reacting and the yielded product. After getting the formula, identify first the hardest element/atom to be balanced such as Na, Zn, Cl, C, O, etc. Then proceed to the easier ones such as O, H. Make sure to note the atoms present in the molecule of the substance.

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.