Answer:
d = 3.44 *10^{-7} m 
Step-by-step explanation:
given data:
length of metal plates = 16.50 cm
capacitor charge = 18.5 nC
potential difference = 37.8 V
capacitance of parallel plate capacitor 

area of the individual plate
 A=
 m2
 m2
capacitance
 

separation between plates d is given as


d = 3.44 *10^{-7} m