Is acetone a protic or an aprotic polar solvent?

Acetone is a polar aprotic solvent.

A solvent is polar if it has a dipole moment greater than 1.6 D and a dielectric constant greater than 5.

The values for acetone are µ = 2.88 D and ε = 21. So acetone is a polar solvent.

A protic solvent has an H atom bound to O or N. It can use its H atom to participate in H-bonding.

An aprotic solvent does not have an H atom bound to O or N, but it can participate in H-bonding with protic molecules.

Acetone does not have an O-H group, but it has a C=O group that can participate in H-bonding.

So acetone is a polar aprotic solvent.

Some other polar aprotic solvents are listed below.