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

Rhodium IridiumRhenium Gallium

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.

27. =3,500,000 x 4,000 = 14,000,000,000

Following are the  advantages of the parametric equations: 1) they can be used to graph curves that are not functions, like the unit circle.2) the parameter can be used to represent the quantity that is  useful to  provide us with better information about the graph.3)  it is useful to convert between rectangular equations and parametric equations.with specific reference to chemistry,  parametric equations are employ for solving hydrogen and hydrogen-like ions, quantum mechanically. herein, cartesian coordinates are converted in spherical polar coordinates. the solution obtained, when plotted on spherical polar graph paper, provides visualization of atomic orbital such as s,p,d and f.