question_answer

Carbon, silicon and germanium have four valence electrons each. At room temperature, which one of the following statements is most appropriate?                                   [AIEEE 2007]

A) The number of free conduction electrons is significant in C but small in Si and

B) The number of free conduction electrons is negligibly small in all the three

C) The number of free electrons for conduction is significant in all the three

D) The number of free electrons for conduction is significant only inandbut small in C

Correct Answer: D

Solution :

[d] The number of free electrons for conduction g significant only in Si andbut small in C, as C is an impurity.