A semi-conductor is damaged & behaves like a conductor, on passing a strong electric current through it, because it heats up the crystals & breaks the covalant bonds resulting in __________ electrons.

ANS:B - excess of

A semiconductor is damaged and behaves like a conductor when a strong electric current is passed through it because the heat generated by the current can break the covalent bonds in the crystal lattice structure of the semiconductor. This process can create additional free electrons and holes, leading to an increase in the number of charge carriers, and thus, enhancing its conductivity. So, the correct option is: excess of electrons.