Answer
190 mL/second.
Work Step by Step
The electrical power used by the magnet is sent into the water as heat/second.
Equate the 2 expressions for power.
$$IV=\frac{Q_{absorbed}}{t}=\frac{mc\Delta T}{t}$$
$$\frac{m}{t}=\frac{IV}{c\Delta T}$$
Assume that 240 V is given to 3 significant figures.
$$=\frac{(21.5A)(240V) }{(4186J/kg C)(6.5C)}\approx 0.190kg/s=190 mL/s$$
