An electric kettle takes 4A current at 220 V. How much time will it take to boil 1kg of water from temperature $20^{\circ}C$ ? The temperature of boiling water is $ 100^{\circ}C$.

Question

$\begin {array} {1 1} (1)\;4.2\: min & \quad (2)\;6.3\: min \\ (3)\;8.4\: min & \quad (4)\;12.6\: min \end {array}$