Which I found correctly to be 6.2 x 10^-3 m^2 by using the formula C= k(8.85x10^-12)A/d

What is the maximum voltage that can be applied to this capacitor without causing dielectric breakdown?

2. I know V=Q/C, and that I have C, but I'm not sure what to substitute for Q, or if I need another formula completely. Help?