The unit of electric potential difference is $.....$

Two students perform experiments on series and parallel combinations of two given resistors $R_{1}$ and $R_{2}$ and plot the following $V-I$ and $I-V$ graphs. Which of the graphs is (are) correctly labelled in terms of the words 'series' and 'parallel'? Justify your answer.

An electric kettle of $2 kW$ works for $2 h$ daily. Calculate the $(a)$ energy consumed in $SI$ and commercial units, and $(b)$ cost of running it in the month of June at the rate of ₹ $3.00$ per unit.

Out of the two wires $X$ and $Y$ shown below,which one has greater resistance? Justify your answer.

Two identical resistors,each of resistance $2 \Omega$,are connected in turn: $(i)$ in series,and $(ii)$ in parallel to a battery of $12 \text{ V}$. Calculate the ratio of power consumed in the two cases.

What is the commercial unit of electrical energy? Represent it in terms of joules.