Why the following compound is not stable? H H O H\, H-C H-C. H C=C H H because the bond angles at the triple-bonded carbons, when the bonding orbitals overlap maximally, are 180 and therefore the sp-hybridized carbons can not simultaneously bind atoms other than hydrogen on both sides of triple-bond because the bond angles at the triple-bonded carbons, when the bonding orbitals overlap maximally, are 120 and 120 angle cannot fit into the ring structure of such a size. because the bond angles at the triple-bonded carbons, when the bonding orbitals overlap maximally, are 180 and 180 angle cannot fit into the ring structure of such a size. because the bond angles at the triple-bonded carbons, when the bonding orbitals overlap maximally, are 120 and therefore the sp-hybridized carbons can not simultaneously bind atoms other than hydrogen on both sides of triple-bond