Carbon, silicon and germanium have four valence electrons each. The most appropriate statement for these elements (at room temperature) is

Options

A. The number of free conduction electrons is negligibly small in all the three
B. The number of free electrons for conductions is significatn in all the three
C. The number of free electrons for conduction is significant in all the three.
D. The number of free conduction electrons is significant in C but small in Si and Ge

Answer

B

Explanation

C, Si and Ge have the same lattice structure and their valence electrons are 4. For C, these electrons are in the second orbit. In solid and germanium it is the fourth orbit. In solid state, higher the orbit, greater the possibility, of overlaping of energy bands. Ioniozation energies are also less therefore Ge has more conducitivity compared to Si. both are semiconductors. Carbon is an insulator.