Reorder the elements aluminum, oxygen, fluorine, calcium, and hydrogen from the least to the greatest number of protons. use the periodic table if needed.

Explanation:

Atomic number means the sum of total number of protons present in an element.

Atomic number of aluminium is 13. So, it has 13 protons.

Atomic number of oxygen is 8. So, it has 8 protons.

Atomic number of fluorine is 9. So, it has 9 protons.

Atomic number of calcium is 20. So, it has 20 protons.

Atomic number of hydrogen is 1. So, it has 1 proton.

Hence, the given elements are arranged from the least to the greatest number of protons as follows.

           Hydrogen < Oxygen < Fluorine < Aluminium < Calcium