Arrange the following in increasing order of their conductivity
(A) Silicon
(B) Germanium
(C) Sodium
(D) Glass
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (D), (A), (B), (C)
Materials are classed by the size of their conductivity. Conductors (metals) have very large conductivity, insulators such as glass have a very small one, and semiconductors such as silicon and germanium lie in between. For the four given materials:
(D) Glass: an insulator, the lowest.
(A) Silicon: a semiconductor.
(B) Germanium: a semiconductor. Its band gap is smaller than that of silicon, so more electrons are excited into the conduction band at room temperature and it conducts better.
(C) Sodium: a metal, the highest.
In increasing order of conductivity:
\( \displaystyle \text{glass} \lt \ce{Si} \lt \ce{Ge} \lt \ce{Na} \)
Shortcut: The insulator (glass) comes first and the metal (sodium) last: only Options (1) and (2). Germanium conducts better than silicon, so (A) comes before (B): Option (1).
NCERT (2026-27 edition):
Conductance of Electrolytic Solutions – …
