As the others have mentioned before me, technically, the answer is 'no'.
But from a business standpoint, leaving buyers' questions to dangle does not make for good business practices. Is the problem that you, as a buyer, are not getting satisfaction? Perhaps the seller is ignoring you on purpose for some reason. Or maybe they are just exceptionally poorly organized. Either way, I would pass on that seller and spend my money elsewhere since a seller that cannot be motivated to gain your custom won't be one willing to work with you afterwards if there is a problem with the purchase.
Alternatively, if you as the seller are being inundated by silly or belligerent questions, perhaps look at your Item Description to see if it suffices. And if the questions are all the same, consider checking the box that posts your Q & A to the listing.
