Which of the following is correct about the electronic (metallic) conductance of a metal such as copper?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → It decreases with increase of temperature.
Conduction through a metal is metallic or electronic conductance: it is carried by the movement of electrons. It depends on the nature and structure of the metal, the number of valence electrons per atom and the temperature, and it decreases as the temperature rises. (The conductance of an electrolytic solution, on the other hand, increases with temperature.)
Why the other options are incorrect
Option (2) It is due to the movement of metal ions through the metal. — Incorrect. The charge in a metal is carried by electrons; movement of ions is the mechanism of electrolytic (ionic) conductance.
Option (3) It changes the composition of the metal as the current flows. — Incorrect. Electrons enter at one end and leave at the other, so the composition of a metallic conductor remains unchanged.
Option (4) It depends on the size of the ions produced and their solvation. — Incorrect. The size of the ions and their solvation affect the conductivity of an electrolytic solution; a metal produces no ions in a solvent.
NCERT (2026-27 edition):
2.4 Conductance of Electrolytic Solutions – “Electrical conductance through metals is called metallic or electronic conductance and is due to the movement of electrons. The electronic conductance depends on (i) the nature and structure of the metal (ii) the number of valence electrons per atom (iii) temperature (it decreases with increase of temperature).”