Qe7 is a checkmate. However, there is another way to checkmate the black king as well. What is it?

You already know that moving Queen to f7 is a stalemate (draw). What is the other move here that leads to a stalemate?

Exercise 1. White to play and checkmate the black king in one move.

Exercise 2. Black to play and checkmate white king in one move.

Exercise 3. White to move. After Qxc7, is it Checkmate or Stalemate?