Alright here’s the solution.

First, the second one.

2. A chessboard is arranged such that each white square is completely surrounded by black squares, and each black square is completely surrounded by white squares. This means that each jenga piece must occupy exactly one white and one black square.

Ok. So what?

A chessboard has an equal number of white and black squares, but when you take away opposite corners (which are always the same color), there are an uneven number of white and black squares.

If there are an uneven number of white and black squares, and each jenga piece must occupy exactly one of each, it is impossible to cover the entire board with jenga pieces!

1. Again, I am going to use the fact that each square is surrounded by squares of the opposite color.

SeBastion starts on a8, a white square. On his first move, whatever that move may be, his only options are black squares. His second move must be a move to a white square. His third move must be to a black square, and so on. Each move alternates between white and black squares. You can list them if you want:

black white black white ….

Notice that after an odd number of moves, Sebastion will be on a black square, and after an even number of moves, he will be on a white square.

If he is to touch every square exactly once, it will take him 63 moves to get to the opposite corner (64 total squares - 1 square he is already on).

Wait a minute. 63 is odd, so his last move should land him on a black square. But the opposite corner is a white square. It’s impossible!