Question

When a fish expands its air bladder, the density of the fish

decreases.increases. remains the same.none of the above

Answer 1

Answer: decreases

Every substance, body or material has mass and volume, however the mass of different substances occupy different volumes.

This is where density
`D` appears as a physical characteristic property of matter that establishes a relationship between the mass
`m` of a body or substance and the volume
`V` it occupies.

`D=(m)/(V)`

So, according to this equation, the density is inversely ptoportional to the volume:

If the volume increases, the density decreases.

This is what a fish does to have buoyancy, since the density of a body is related to its buoyancy:

A body will float on another fluid if its density is lower.

This is what the fish does when it expands its air bladder, incrementing its volume, hence decreasing its density.