To study the dependence of current $\left(I\right)$ on the potential difference $\left(V\right)$ across a resistor, two students used the two setups shown in figs. $\left(A\right)$ and $\left(B\right)$ respectively. They kept the contact $J$ in different positions marked (1), (2), (3), (4) in the two figures.
       
For the two students, their ammeter and voltmeter readings will be minimum when the contact $J$ is in the position:

While performing the experiment to study the dependence of current on potential difference across a resistor, following observations were made by four students $A, B, C$ and $D$.

The student who made the wrong observation is 

To determine the equivalent resistance of two resistors, when connected in series, the correct way of connecting the ammeter and voltmeter in the circuit is:

A $6 \mathrm{V}$ battery (of internal resistance $2 \mathrm{\Omega }$) is connected across a $10 \mathrm{\Omega }$ resistor and a switch in series, as shown:

If the switch is kept in the off position, as shown in the figure, then:

The number of divisions in ammeter of range $2 \mathrm{A}$ is $10$ and voltmeter of range $5 \mathrm{V}$ is $20$. When the switch of the circuit given below is closed, ammeter reading is at $8^{\mathrm{th}}$ division and voltmeter reading is at $8^{\mathrm{th}}$ division. The value of resistance of the resistor is