Out of the following, non-ohmic resistor is :

1. nichrome
2. copper sulphate solution with copper electrodes and dil sulphuric acid.
3. solar cell
4. silver

solar cell

Reason — Nichrome, Copper sulphate solution with copper electrodes and dil sulphuric acid, Silver, all the three follow Ohm's Law i.e., V = IR, hence they are ohmic conductors whereas a solar cell is a non-ohmic conductor.