A metal sphere is kept on an insulating stand. A negatively charged rod is brought near it, then the sphere is earthed as shown. On removing the earthing, and taking the negatively charged rod away, what will be the nature of charge on the sphere?

A rod is brought close to the sphere, the free electron in the sphere move away due to deficit of electrons. The process of change distribution stops when the net force on the free electron inside the metal is less. When we connect the sphere to the ground electron will flow to the ground while the charge will remain on the sphere. So final charge on the sphere will be positive.