The energy band gap (distance between the conduction band and valence band) in conductor is:
(A) 0
(B) $4{{A}^{0}}$
(C) $10{{A}^{0}}$
(D) $100{{A}^{0}}$

Hint: We know that the conduction band is the band of electron orbitals that electrons can jump up into from the valence band when excited. When the electrons are in these orbitals, they have enough energy to move freely in the material. In non-metals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. The band occupied by these electrons is called a conduction band. The separation between valence band and conduction band is known as forbidden energy gap. If an electron is to be transferred from valence band to conduction band, external energy is required, which is equal to the forbidden energy gap.

Complete step by step answer
We know that the energy band definition is, the number of atoms within a crystal stone can be nearer to each other as well as a number of electrons will interact with each other. The energy levels of electrons within their shell can be caused due to the changes in their energy levels. Energy band theory is a theory of a valence electron moving in a periodic potential field of a crystalline lattice. Single atoms have a discrete energy spectrum, which means they can occupy only discrete energy levels. Part of these levels can be occupied only when electrons are excited.
It is known that electronic states, also known as energy levels or energies, are sites in an atom or a crystal that an electron can reside in. In a semiconductor, these sites are found in the valence band and in the conduction band and vary from semiconductor to semiconductor. They are like a bookshelf, with shelves at certain heights.
It is known that the conductors, the valence band and conduction band overlap each other or have the extremely small energy gap between them approximately equal to zero.

So, the correct answer is option A.

Note: We know that the conduction band is the band of electron orbitals that electrons can jump up into from the valence band when excited. When the electrons are in these orbitals, they have enough energy to move freely in the material. This movement of electrons creates an electric current. The gap between the valence band and conduction band is called the forbidden energy gap. The valence electrons, while going to the conduction band, pass through this. In a semiconductor or an insulator there is a valence band containing many states, most of which are occupied. Above this is a forbidden band with only a few isolated states caused by impurities. Fermi energy is a concept in quantum mechanics usually referring to the energy difference between the highest and lowest occupied single-particle states in a quantum system of non-interacting fermions at absolute zero temperature.