"Is dry cake normal?"
Translation:Ĉu seka kuko estas normala?
That should be acceptable, but it's unusual word order in my experience, and might be misleading ("garden-pathing") since I would understand "Ĉu estas seka kuko?" as meaning "Is there any dry cake?" and then suddenly there comes a "normala" and I have to re-parse the sentence to have the estas not existential but copular.
Do we always need to add "cxu" before every close-ended question?
Can "Estas seka kuko normala?" be accepted?