Acetone = A, n – butane = B, methoxy ethane = C, Protan – 1 – ol = D ; Propanal = E. Decreasing order of boiling points is

D > A > E > C > B.

Inter molecular hydrogen bonding in Alcohols;

Dipole-dipole attractions in carbonyl compounds ( Ketones > Aldehydes ).

Weak dipole-dipole attractions in Ethers.

Very weak London dispersion forces in Alkanes.