Can you promote a pawn to a second Queen?

Promotion in chess is a rule that requires a pawn that reaches the eighth rank to be replaced by the player's choice of a bishop, knight, rook, or queen of the same color . The player cannot convert the pawn to another king nor another pawn.

Why would you not promote a pawn to a queen?

This happens because of one of these move types. To avoid stalemate and win eventually, you have to select a promotion which doesn't have stalemating move, which is called underpromotion. For example, if diagonal move stalemates, you can't select queen as it has diagonal move ability.

What happens if the Queen is captured in chess?

If you mean if you've just taken the opponent's Queen with your peice, Then it means you win. Thats how you win, Capture the queen. lol – game ends when you checkmate the king. Queen is a powerful piece, but king is the king.

Can a pawn check a queen?

It's still perfectly legal to drop a pawn that gives check though (and to check/mate normally with a pawn), so this a much less severe restriction than what your question asks about. But this is a case in which the pawns are singled out, because any other piece can be dropped to give an immediate checkmate.