Calvin touches a negatively charged rod to a neutral metal sphere located on an insulated stand. What will happen to the electrons when the negatively charged rod touches the metal sphere?

When the negatively charged rod touches the metal sphere, electrons from the rod will transfer to the sphere. This is due to the principle of charge neutrality, which states that the total charge of a system should remain constant. This transfer of electrons will cause the metal sphere to become negatively charged as well.