Limitations of Ohm's Laws

Current(I)- voltage$\left(V\right)$ characteristics of two elements $A$ and $B$ are as shown
[figure $\left(a\right)$and $\left(b\right)$]

An example of non-ohmic resistance is:

The example of non ohmic resistance is _____ .

Substances that have constant resistance over a wide range of voltages are

Give two examples of non-ohmic devices.

A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances $R1, R2, R3$ respectively. Which of the following is true?

The resistance of a wire is $5 \mathrm{\Omega }$ at $50 °\mathrm{C}$ and $6 \mathrm{\Omega }$ at $100 °\mathrm{C}$. The resistance of the wire at $0 °\mathrm{C}$ will be,

The resistance of a discharge tube is

The resistance of a discharge tube is,