Answer:
The value of resistor is 525.76 ohms
Step-by-step explanation:
Given;
capacitance, C = 2.6 μF = 2.6 x 10⁻⁶ F
let the initial charge on the capacitor = Q₀
time , t = 2.2 ms = 2.2 x 10⁻³ s
The discharge of the capacitor is given by;

Where;
Q(t) is the charge after 2.2ms = 20% of Q₀ = 0.2Q₀

Therefore, the value of resistor is 525.76 ohms