What type of electric charge does a proton possess?

Which of the following materials has the highest number of free electrons?

The voltage-current variation of two metallic wires $X$ and $Y$ at constant temperature are shown below. Assuming that the wires have the same length and the same diameter, explain which of the two wires will have larger resistivity.

Calculate the number of electrons constituting one coulomb of charge. (Charge on one electron $= 1.6 \times 10^{-19} \text{ C}$)

What is the main principle involved in a Voltaic cell?

Which of the following combinations of cells in series (as shown in the figure) correctly represents the arrangement to obtain maximum potential?