Starting with the rarest put the following metals in order by their availability 1. gallium 2. rhenium 3. iridium 4. rhodium

Explanation:

A brief introduction to these rarest metals.

Rhodium:

Rhodium is a chemical element with symbol Rh. it is a rare silvery, white, hard and chemically inter transition metal. It is a member of the platinum group. it is considered as the most valuable precious metal in the world.

Iridium:

Iridium is a chemical element with symbol Ir. Iridium is used in making crucibles and other equipment that is used at high temperature.  it is also using in spark plugs because of its high melting point and has low toxicity.  

Rhenium:

Rhenium is a chemical metal with symbol Re. The most common commercial use of Rhenium is in the alloys that make up jets. Rhenium is less reactive to air than magnesium, which is two places above Rhenium in the periodic table.

Gallium:

Gallium is a chemical element with symbol Ga. Element gallium is a soft, silvery blue metal at standard temperature and pressure. Gallium is used to produce solid -state items like transistors and light emitting diodes.

12 is it do you think so

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.