Objects: a balloon full of helium in the air. air- 1.27 kg/ml or helium balloon- 0.33 kg/ml
which has a greater density? will the object sink or float?

Air has greater density.

The object will float.

Explanation:

Density of a body is defined as the mass of a body per unit volume of it.

Here, air has a density of 1.27 kg per ml and Helium balloon has a density of 0.33 kg per ml. This means that if volume is 1 ml, then the mass of air in that volume will be 1.27 kg and mass of Helium balloon in that same volume will be 0.33 kg.

Therefore, the mass of Helium balloon is lighter than that of air in a given volume. Hence, air is heavier and has a greater density.

A lighter density object always floats over a greater density body.

Hence, Helium balloon will float over air as Helium balloon is less dense than that of air.