When two conducting spheres are brought into contact, the charges on the spheres redistribute until they reach equilibrium. This redistribution of charge occurs in such a way that the total charge on the two spheres is conserved. This means that the sum of the charges on the spheres before and after contact remains the same.
Option 1: The statement that the total energy of the two spheres is conserved is not correct. When the spheres are brought into contact, there may be a transfer of electrical potential energy between the spheres. Therefore, the total energy of the system may not be conserved.
Option 3: This option claims that both the total energy and charge are conserved, which is incorrect. As mentioned earlier, the total energy of the system may change due to the redistribution of charge.
Option 4: The statement that the final potential is always the mean of the original potentials of the two spheres is not necessarily true. The final potential depends on the initial charges and the sizes of the spheres.
Alert - correct answer should be option 2.