This is a bit of a tricky question, as it depends on what you mean by "heavier".

Here's the breakdown:

* Mass: Objects in a vacuum and in air have the same mass. Mass is the amount of matter in an object and doesn't change based on its surroundings.

* Weight: Weight is the force of gravity acting on an object's mass. In a vacuum, an object's weight would be slightly less than in air due to the absence of air resistance.

* Density: Density is mass per unit volume. Objects in a vacuum and in air have the same density.

So, while an object might feel "lighter" in a vacuum due to the lack of air resistance, it's not actually lighter in terms of mass or density.

In short:

* Mass: Same in vacuum and air

* Weight: Slightly less in vacuum

* Density: Same in vacuum and air

Let me know if you have any other questions!