You have two square metal plates with side lengths of (6.50 C) cm. You want to make a parallel-plate capacitor that will hold a charge of (12.5 A) nC when connected to a (34.8 B) V potential difference. Determine the necessary separation in mm. Round your answer to three significant figures.

The necessary separation between  the two parallel plates is 0.104 mm

Explanation:

Given;

length of each side of the square plate, L = 6.5 cm = 0.065 m

charge on each plate, Q = 12.5 nC

potential difference across the plates, V = 34.8 V

Potential difference across parallel plates is given as;

Where;

d is the separation or distance between the two parallel plates;

Therefore, the necessary separation between  the two parallel plates is 0.104 mm

whichever one it is, it's definitely not one that you included on the list you provided.