JEE MAIN - Physics (2007 - No. 4)
Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate ?
The number of free electrons for conduction is significant only in $$Si$$ and $$Ge$$ but small in $$C.$$
The number of free conduction electrons is significant in $$C$$ but small in $$Si$$ and $$Ge.$$
The number of free conduction electrons is negligibly small in all the three.
The number of free electrons for conduction is significant in all the three
Explicació
$$Si$$ and $$Ge$$ are semiconductors but $$C$$ is an insulator. Also, the conductivity of $$Si$$ and $$Ge$$ is more than $$C$$ because the valence electrons of $$Si, Ge$$ and $$C$$ lie in third, fourth and second orbit respectively.