Which of the following alkynes give exactly one ketone, and nothing else, on Hg(II)-catalysed hydration? Select all that apply.

A symmetrical internal alkyne has the same substituent on each side, so both Markovnikov orientations give the same ketone: but-2-yne gives butan-2-one and hex-3-yne gives hexan-3-one. Pent-2-yne is unsymmetrical and gives a mixture of pentan-2-one and pentan-3-one. Ethyne gives ethanal, an aldehyde.