Question

Which conductor has the highest critical temperature?

Answer 1

A conductor is said to be an object or material that allows electric current to flow through it. Every material has a finite resistance in it. For conductors, this resistivity increases with an increase in temperature and decreases with a decrease in temperature. For some conductors, this resistivity becomes zero at a particular temperature. This temperature is called the critical temperature. Such materials whose resistivity becomes zero are called superconductors.

Complete answer:
As per theoretical science, any substance can become a superconductor when frozen to an appropriate temperature. The first element that was found to have properties of superconductors was mercury with a critical temperature of $4K$.
The answer to the above question which conductor has the highest critical temperature is that Mercury Barium Thallium Copper oxide. Currently, this is the superconductor that has recorded the highest critical temperature. It has a critical temperature of $139K$ in one atmosphere. This superconductor is one type of ceramic copper oxide.

Note:
When we raise the temperature of a substance, the molecules will start moving in a rapid motion As a result there will be two outcomes. One is the density of the liquid goes down. And the other one is the vapor pressure goes up. This in turn raises the density of the vapor. At some point, the temperature of the vapor becomes so high. This makes the density of the vapor equal to the density of the liquid. This makes it difficult to differentiate between vapor and liquid. This temperature is called critical temperature. At this point, the molecular movement will become so high that the attracting forces acting on it are insufficient to cause them to condense into liquid form.