An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?

The force responsible for the attraction between the balloon and the wall is electrostatic force. On rubbing the balloon with a piece of synthetic cloth, both the balloon and cloth acquire equal and opposite charges. Opposite charge develops on the wall due to induction and both balloon and wall get attracted to each other when the balloon is pressed against the wall.