Ametal sphere, x, has an initial net charge of −6 × 10−6 coulomb and an identical sphere, y, has an initial net charge of +2 × 10−6 coulomb. the spheres touch each other and then separate. what is the net charge on sphere x after the spheres have separated?

When the two spheres touch each other, part of the charge recombine together. The part of charge that recombines is the excess of positive charge on sphere Y, , that recombines with an equivalent charge of  located on sphere X. As a result, the total charge remained on the two spheres is the excess of negative charge remained on sphere X:

Since the two spheres are identical, they have same capacity, so this charge will now redistribute equally on the two spheres: therefore, at the end, each sphere will have