Question

A solid with high electrical and thermal conductivity from the following is
A.$Si$
B.$Li$
C.$NaCl$
D.$ice$

Answer 1

Hint:Thermal and electrical conductivity are related to each other. In metals they are proportional in materials .They may depend upon temperature gradient, property of metal.

Complete step by step answer:
Firstly we have to know about what thermal conductivity is and what is electrical conductivity?
Thermal conductivity may be defined as is a measure of its ability to conduct heat .It is commonly denoted as $k,\lambda $ .Heat transfer occurs at lower rate in material of low thermal conductivity than in material of high thermal conductivity. For instance, generally metals typically have high thermal conductivity and are very efficient at conducting heat, while the opposite is true for insulating materials. They are used in heat sink applications. The SI unit of thermal conductivity is watts or meter kelvin.
Electrical conductivity may be defined as how much voltage is required to get an amount of electric current to flow. This is largely defined by the no of electrons in the outermost shell; these electrons determine the ease with which mobile electrons are generated.
Now, came to the solution part like the other alkali metals lithium has a single valence electron which is readily available for delocalization and contribution. This is because of lithium is a good conductor of heat and electricity
Hence, option B is the correct answer.

Note: Lithium also has the highest lattice energy among alkali metals, because lattice energy depends upon the ratio of charge to size. Smaller the size larger the lattice energy and same as for hydration energy .Diamond is the leading thermally conductive material and has conductivity value measure 5 times higher than copper.