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Steven Parker216,136 Points
By "tag", I expect you are asking about the HTML. In that case, no, an element can have only one ID; and that ID must be unique on the page. On the other hand, an element can have multiple class names, and those work much the same as ID's for CSS selectors.
But if you meant to ask if a CSS rule can apply to more than one tag selector — then yes, the selectors can be listed separated by commas.
HIDAYATULLAH ARGHANDABI21,017 Points
Logically you can use on id selector to apply all styling attributes to it.