Question

Thermal expansion of a solid is due to the

• A. symmetric characteristic of the inter atomic potential energy curve of the solid
• B. asymmetric characteristic of the inter atomic potential energy curve of the solid
• C. double well nature of the inter atomic potential energy curve of the solid
• D. rotational motion of the atoms of the solid

Answer 1

Answer: (B)

An approximate potential energy curve for two particles is as shown below.

Here $E_1 ,E_2$ and $E_3$, are the total energy
values of particles. As temperature increases, total energy $E$ increases.
Hence, mean separation $r$ also increases. Note That mean separation $r$ is mid point of length of $E$ intercepted by potential energy curve.