We can calculate the density of the balloon as follows:
![\rho=(mass)/(volume)=(1000g)/(1000cm^3)=(1g)/(cm^3)](https://img.qammunity.org/2023/formulas/physics/college/5r2rqwbyk9s72ssr5emakvdt9y51bezkug.png)
Therefore, the balloon will fall
Since the density of air is about 0.00123 g/cm^3 , the balloon is much more dense than the surrounding air. As a result, the balloon weighs more than the air that it displaces so the balloon will fall.