Answer:-

i. Conduction band : The highest energy band containing electrons is the conduction band. It is formed by interaction of the outermost energy levels of closely spaced atoms in solids. Conduction band may be partially occupied or vacant. Electrons in conduction band are mobile and delocalized over the entire solid.They conduct electricity when electrical potential is applied.
ii. Valence band : The band having lower energy than conduction band is the valence band.  The electrons in valence band are not free to move because they are tightly bound to the respective nuclei.