All of the classes of compounds contain at least one
oxygen atom EXCEPT
(A) esters (B) aldehydes
(C) ethers (D) alkynes
Esters have the functionality R-CO-OR', the oxygen in the CO part is double bonded to carbon.
Aldehyde functionality have the functionality R-CHO, the oxygen in the CHO part is double bonded to carbon.
Ether functionality is R-O-R', R and R' are alkyl groups, similar or dissimilar.
Alkynes have the structural feature R-C.C-R'.There is a triple bond between the two central carbon atoms, shown as C.C
Therefore, alkynes do not have an oxygen atom within them.