The current in a circuit containing a battery connected to 2Ω resistance is 0.9 A. When a resistance of 7Ω connected to the same battery, the current observed in the circuit is 0.3A. Then the internal resistance of the battery is
(1) 0.1 Ω
(2) 0.5 Ω
(3) 1 Ω
(4) Zero
