Ans: This is possible. We can imagine that between the white king and black rook, there was another piece. The queen can capture it and checkmate. Hence, it's Qxb4#
well if we forget about the black king not being there it is possible there could have been a picec blocking the check then the queens takes it, it looks impossible but its not
Ans: This is possible. We can imagine that between the white king and black rook, there was another piece. The queen can capture it and checkmate. Hence, it's Qxb4#