Answer:
![5\cdot 10^(-9) F](https://img.qammunity.org/2020/formulas/physics/high-school/ejms1ymiy1a2zp99tvhoam25j89aolw40y.png)
Step-by-step explanation:
The capacitance of the electrode is given by:
![C=(Q)/(V)](https://img.qammunity.org/2020/formulas/physics/middle-school/ay5lam86x794vxez64ahc4r3kfksm66rut.png)
where
C is the capacitance
Q is the charge on the electrode
V is the potential difference
In this problem, we have
![Q=45 nC=45\cdot 10^(-9) C](https://img.qammunity.org/2020/formulas/physics/high-school/6a02e2a47jga57lsjwqy2f51xdhzqjd6im.png)
V = 9.0 V
Substituting into the equation, we find
(5 nF)