electrostatics

see this is not very difficult

first.. the toal no of moles of cu has to be found in each sphere.

then you find the total no of molecules there that is by multiplying it by avogadro's number

now find the total no of protons in the nucleii by multiplying it by the atomic number

multiply by charge of one proton to get the total charge on it

1% of thta is the new charge on each sphere..

Now you can solve it :)