Question

In which of the following does the residual resistivity exist?

(a) Impure metal at high temperature

(b) Pure metal at low temperature

(c) Pure metal at high temperature

(d) Impure metal at low temperature

This question was posed to me in an international level competition.

My doubt stems from Hall Effect in division Semiconductors of Engineering Physics II

Answer 1

The correct answer is (d) Impure metal at low temperature

The best I can explain: When the temperature is reduced to 0K, the resistivity of the impure metal doesn’t become zero, because there exist some impurities which gives rise to minimum resistivity known as residual resistivity.