"penultimate question" is correct and usable in written English.
You would typically use it to refer to the next-to-last question in a series or comparison. For example, "The penultimate question on the final exam was the hardest one of all."
PR: The penultimate question.
Scarborough's penultimate question was to ask Koch how he had learned such "graciousness".
For the penultimate question of the debate, Hill asked what the most valuable thing they each received from hearing the other person's point of view.
I don't know if it's something to do with the moment, or if it's just because Barry Hines seems such a kind man, but my penultimate question comes out as a bit of a blurt.
The penultimate question is going to be the second-most quoted bit of the debate, but not for the question or the answer from Hillary Clinton.
The Commons opens at 11.30am with International Development questions, followed by the penultimate prime minister's questions of this Parliament.
He even trounced Tony Blair at the penultimate prime minister's question time, a rare outcome.
After Schumacher gave a flippant response at the penultimate race to a question about how he would sum up his year — "Good fun!" he said — he was asked what he could offer the team next year, considering that his teammate had been a little faster than him all season.
Ed Miliband used the penultimate prime minister's questions before the general election, and the session immediately before the budget, to attack the government's record on the NHS.
The Lady Bamford-owned filly had finished third in the Epsom Oaks on her penultimate start, but had questions to answer following a meek reverse in France in June.
The general election campaign took centre stage in the penultimate First Minister's Questions in Holyrood.
