If R= 2 ohm, the potential difference across 2R resistance will be **4 volts**.
This can be calculated using the following equation:
V = IR
* V is the voltage
* I is the current
* R is the resistance
If we assume that the current flowing through the 2R resistor is 2 amps, then the potential difference across the resistor will be:
V = 2 amps * 2 ohms = 4 volts
Therefore, the correct answer is **4 volts**.