A Smorgasbord of Chess!

Below are puzzles that (just like in an actual chess game) will have no hints. There is a smorgasbord of possible answers (i.e. great positional moves, great opening play, winning tactics, subtle endgame play, etc.) Good luck! Try your luck answering them but really the main benefit is derived from understanding the answer (whether you got the puzzle "right" or "wrong").