Identify the correct statement(s) from the following Resistivity ( ρ…

The correct answer is Option (2) → (A) and (C) only

The three graphs show the three types of behaviour of resistivity with temperature: a metal, an alloy and a semiconductor.

(A) Graph (i), shows \( \rho \) versus T variation for Copper — Correct. The resistivity is of the order of \( 10^{-8}\,\Omega\,\mathrm{m} \) and rises with temperature, as for a metal.

(B) Graph (ii), shows \( \rho \) versus T variation for Silicon — Incorrect. Graph (ii) shows a large resistivity (in \( \mu\Omega\,\mathrm{cm} \)) that rises only slightly and linearly with temperature, which is the behaviour of an alloy such as nichrome. Silicon is a semiconductor, whose resistivity falls with temperature.

(C) Graph (iii), shows \( \rho \) versus T variation for semiconductor — Correct. The resistivity falls as the temperature rises, because more carriers are released.

(D) Graph (iii), shows \( \rho \) versus T variation for Nichrome — Incorrect. Nichrome has a high resistivity that changes very little with temperature; its resistivity does not fall steeply as in graph (iii).

NCERT (2026-27):
Resistivity of Various Materials – “… In between the two are the semiconductors. These, however, have resistivities characteristically decreasing with a rise in temperature.”

Temperature Dependence of Resistivity – “… For metals, \( \alpha \) is positive. The relation of Eq. (3.26) implies that a graph of \( \rho_T \) plotted against T would be a straight line. At temperatures much lower than 0°C, the graph, however, deviates considerably from a straight line (Fig. 3.8).”

Temperature Dependence of Resistivity – “… Some materials like Nichrome (which is an alloy of nickel, iron and chromium) exhibit a very weak dependence of resistivity with temperature (Fig. 3.9).”