The correct sequence of conductivity of the following materials at 300 K in the increasing order is

(A) Copper
(B) Graphite
(C) Germanium
(D) Silicon

Choose the correct answer from the options given below:

(D), (C), (B), (A)

The correct answer is Option (4) → (D), (C), (B), (A)

Electrical conductivity at 300 K (room temperature) for the given materials:

• Silicon (Si) → semiconductor, low conductivity
• Germanium (Ge) → semiconductor, higher conductivity than Si
• Graphite → good conductor (delocalized π electrons)
• Copper (Cu) → excellent conductor, highest conductivity

Increasing order of conductivity:

$\text{Si (D)} < \text{Ge (C)} < \text{Graphite (B)} < \text{Cu (A)}$