Band Theory of Metals — Prelims Questions

According to the Band Theory of Solids, which of the following statements correctly describes the electrical conductivity of a metal?

A material has a completely filled valence band and an empty conduction band, separated by an energy gap of $0.8,\text{eV}$. What type of material is this, and how will its conductivity change with increasing temperature?

Which of the following statements is INCORRECT regarding the Band Theory of Solids?

Which of the following materials would exhibit the highest electrical conductivity at room temperature based on its band structure?

In the context of band theory, what happens when a semiconductor is doped with an impurity?

Consider two materials, P and Q. Material P has a band gap of $0.1,\text{eV}$, and Material Q has a band gap of $4.5,\text{eV}$. Which material will show a significant increase in conductivity when heated from $0,\text{K}$ to room temperature?