Ethanol and dimethyl ether have different chemical and physical properties because they have different

(1) functional groups

(2) molecular masses

(3) numbers of covalent bonds

(4) percent compositions by mass

The correct answer is option 1. Ethanol and dimethyl ether have different chemical and physical properties because they have different functional groups. Ethanol is an alcohol while the latter is an ether. They have different functional groups and different structures thus different properties.