Dear student,
There will be distribution of charges...
Linear Charge Density(l)
Let a charge q be uniformly distributed along a length l, then the linear

SI unit of linear charge is C/m.
Surface Charge Density
Suppose a charge q is uniformly distributed over a surface of area A.
Then the surface density s defined as the charge per unit area.

						

							
To answer your initial question, nothing will happen. "Insulated" implies they are non conducting. So charges are not free to move on them and hence there shall NOT be a distribution of charges. If they were conducting, charges would flow between them until they acquire the same potential. Thus finally they would each have a charge of (Qa + Qb)/2
						

							
Copper is a good conductor of electricity . Right? Insulated here means that charges from copper sphere can't move out from the body. For your better understanding you can assume this- those copper spheres have an insulating handles at the bottom so that the charges present inside them don't flow inside our body when we are holding them . So you can now do your calculations without bothering about any change in the charge of those metallic sphere's...Hope it helped!