Question

In the following solids thermal conductivity is maximum for :
(A) Copper
(B) Aluminium
(C) Gold
(D) Silver

Answer 1

This is a knowledge based question. Transport of thermal energy in solids may be generally due to two effects namely, the migration of free electrons and lattice vibrational waves (photons).Metals are solids and as such they possess crystalline structure where the ions (nuclei with their surrounding shells of core electrons) occupy translationally equivalent positions in the crystal lattice. Metals in general have high electrical conductivity, high thermal conductivity, and high density.

Complete Answer:
Thermal conductivity is an intensive physical property of a material that relates the heat flow through the material per unit area to temperature gradient across the material. The thermal conductivity of a material is basically a measure of its ability to conduct heat.
Materials with a high thermal conductivity can effectively transfer heat and readily take up heat from their environment. Poor thermal conductors resist heat flow and obtain heat slowly from their surroundings. The thermal conductivity of a material is measured in Watts per meter per degree Kelvin ( ${W \mathord{\left/ {\vphantom {W m}} \right.} m} \cdot K$ ).
We take the options provided in the question into consideration one by one.
Copper (Thermal conductivity : $398{W \mathord{\left/ {\vphantom {W m}} \right.} m} \cdot K$ ) is the most commonly used metal for manufacturing conductive appliances in the United States. Copper has a high melting point and a moderate corrosion rate. It is also a very effective metal for minimizing energy loss during heat transfer. Metal pans, hot water pipes and car radiators are all appliances that utilize the conductive properties of copper.
Aluminium ( $310{W \mathord{\left/ {\vphantom {W m}} \right.} m} \cdot K$ ) is frequently used as a replacement for beryllium oxide. Unlike beryllium oxide, aluminium nitride does not impose a health hazard to manufacture yet still displays similar chemical and physical properties to beryllium oxide. Aluminium nitride is one of the few known materials to offer electrical insulation along with a high thermal conductivity. It has extraordinary thermal shock resistance and acts as an electrical insulator in mechanical chips.
Gold ( $315{W \mathord{\left/ {\vphantom {W m}} \right.} m} \cdot K$ ) is a rare and expensive metal that is used for specific conductive applications. Unlike silver and copper, gold rarely tarnishes and can withstand conditions that experience large amounts of corrosion.
Silver ( $429{W \mathord{\left/ {\vphantom {W m}} \right.} m} \cdot K$ ) is a relatively inexpensive and abundant thermal conductor. Silver is a component of numerous appliances and is one of the most versatile metals due to its malleability. 35% of silver manufactured in the U.S is used for electrical tools and electronics (US Geological survey mineral community 2013). A bi-product of silver, silver paste, is increasing in demand due to its use for environmentally friendly energy alternatives. Silver paste is used in the production of photovoltaic cells that are a major component of solar energy panels.
Hence the correct answer is option D.

Note:
Remember that even though copper has lower conductivity than silver, it is used in electrical wiring only because it is cheaper than silver. The high conductivity properties of copper allow for a greater distance of electrical current travel. Besides being inexpensive, copper is also ductile, meaning it can bend and flex.