Answer:

Introduction:
In solid-state physics, the valence band and conduction band are energy bands that describe the behavior of electrons in a material. The valence band is the highest band that is completely filled with electrons at absolute zero temperature, while the conduction band is the lowest empty band above the valence band.

Explanation:
When the temperature of a material is increased above absolute zero (0 K), thermal energy is supplied to the electrons. This thermal energy can cause some of the electrons in the valence band to gain enough energy to overcome the energy gap between the valence band and the conduction band. As a result, these electrons are promoted from the valence band to the conduction band.

Key Points:
- The statement "Electrons from the valence band rise to the conduction band when the temperature is greater than 0 K" is true.
- This phenomenon is known as thermal excitation or thermal promotion of electrons.
- The energy required for an electron to move from the valence band to the conduction band is called the bandgap energy.
- In semiconductors, the bandgap energy is relatively small, allowing thermal excitation to occur at room temperature.
- In insulators, the bandgap energy is larger, requiring higher temperatures or additional external energy sources to promote electrons to the conduction band.
- Once in the conduction band, the electrons can move freely and contribute to the conduction of electric current.
- The movement of electrons from the valence band to the conduction band is essential for the operation of electronic devices such as transistors and diodes.

Conclusion:
In summary, at temperatures greater than 0 K, electrons in the valence band can gain enough thermal energy to move to the conduction band. This process is crucial for the conduction of electric current in materials and is essential for the functioning of electronic devices.