I see no reason why both (4) and (5) should not have plural verbs to match the compound subjects here. Nevertheless, the singular is often considered acceptable, presuming that the speaker is considering one item at a time, in sequence: 'On the table there's a pencil, a notebook, and two coffee cups.'
'1. Do you know when the store is closed?' -- is the only grammatically acceptable option. C'mon, Jack-- you know that (3) is wrong-- why did you submit it?
PS: We gotta stop meeting like this, Cassy-- people will start to talk.
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