Answer:
The magnitude of q = 0.612nC
Step-by-step explanation:
The concept of coulomb's law was applied as it relates to the potential of each surface mentioned in the question. we are considering an inner sphere and a spherical shell each with its own radius.
The potential at each sphere was gotten, thereafter the potential differences between each sphere was equated to get the magnitude of the charge as it is shown in the attached file.
The steps and the mathematical explanation are as shown in the attachment.