Which of the following statements are correct?
(A) The resistivity of a semiconductor decreases with increasing temperature.
(B) The potentiometer is unaffected by the internal resistance of the source.
(C) In ionic crystals and electrolytic liquids electrons carry the electric current.
(D) Ohm's law fails if V depends on I non-linearly.
(E) Kirchhoff's rules are used for analysis of electric circuits.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B), (D) and (E) only
(A) The resistivity of a semiconductor decreases with increasing temperature. — Correct. On heating, the number density of charge carriers rises sharply, so the resistivity falls.
(B) The potentiometer is unaffected by the internal resistance of the source. — Correct. At the balance point no current is drawn from the source, so its internal resistance causes no drop.
(C) In ionic crystals and electrolytic liquids electrons carry the electric current. — Incorrect. In these materials the current is carried by positive and negative ions, not by free electrons.
(D) Ohm's law fails if V depends on I non-linearly. — Correct. Ohm's law says \( V \propto I \), a straight-line graph. If the graph of \( V \) against \( I \) is not a straight line, as in a diode, the law does not hold.
(E) Kirchhoff's rules are used for analysis of electric circuits. — Correct. The junction rule (charge conservation) and the loop rule (energy conservation) are used to find currents and voltages in any circuit.
Note: Statements (A), (C), (D) and (E) of this question are from the latest textbook (2026-27). Statement (B), that the potentiometer is unaffected by the internal resistance of the source, is printed only in the pre-rationalised textbook (2022-23). It was removed from the latest book, and it also appears to be out of the CUET 2026 syllabus.
NCERT (2026-27):
Temperature Dependence of Resistivity – “… Unlike metals, the resistivities of semiconductors decrease with increasing temperatures.”
Summary – “… 6. In most substances, the carriers of current are electrons; in some cases, for example, ionic crystals and electrolytic liquids, positive and negative ions carry the electric current. …
10. Ohm’s law is obeyed by many substances, but it is not a fundamental law of nature. It fails if (a) V depends on I non-linearly.”
Kirchhoff’s Rules – “… Two rules, called Kirchhoff’s rules, are very useful for analysis of electric circuits.”
NCERT (Pre-rationalised edition, 2022-23):
Potentiometer – “… The potentiometer has the advantage that it draws no current from the voltage source being measured. As such it is unaffected by the internal resistance of the source.”