The weight of a balloon, whether inflated or deflated, remains essentially the same. The weight of an object is determined by the amount of matter it contains, which is measured by its mass. In the case of a balloon, the mass is primarily concentrated in the material from which it is made, such as latex or rubber.
When a balloon is inflated, it becomes larger in volume as it fills with air or another gas. The inflation process increases the volume of the balloon without significantly changing its mass. The air or gas inside the balloon has mass, but it is relatively small compared to the mass of the balloon itself.
Therefore, the weight of the inflated balloon is essentially the same as the weight of the deflated balloon. The additional weight of the gas or air inside the inflated balloon is minimal compared to the weight of the balloon material.