The plate current in a diode is 20 mA when the plate voltage is 50 V or 60 V. What will be the current if the plate voltage is 70 V?
For 50 V or 60 V, the plate current is 20 mA. That means 20 mA is the saturation current.
At the given temperature, the plate current is 20 mA for all other values of voltages.
Thus, the current at 70 V will be 20 mA.