Legal or Illegal (yes I know it's old!)

My 1st one.

It is very easy, it is an illegal position. The Rook and queen cannot give check at the same time. Only a heavy piece and a minor piece can do that.

I believe it's legal, but switching white's knight and e pawn would make it illegal.

Maybe it's old but these things are always fun!

The position is legal of course but I'll let someone else find out how (hopefully not one of the "regulars" )

Yep you got it

I believe the position is legal if Black's last move was ... fxg3ep.

This reminds me of a position I saw in Jeff Coakley's "The Puzzling Side of Chess" column:

Two minors can as well, if a knight moves checking the King and causing a discovered check on the King from a Bishop.

Actually, Post #2 is both right and wrong.  It is possible to give check with a Queen and Rook, but not with that configuration.

*** EDIT: I Stand corrected.  En Passant is possible here for double check.  But still, even with out the En Passant, you CAN give double-check with Rook and Queen.

A perfect example of a position where Black can give check with both the Queen and Rook:

1...Rd6+ is double-check where both the Rook and Queen give check.

Legal. White's last move was g4.

Looks like an en passant capture, ...fxg3, has been played in response to g4. That'll open the two lines at once.

And yes if the pawn were on e2 then the whole thing would be illegal because the g2 pawn has to leave g2 at that specific moment, and with pawns on e2 and g2 the bishop wouldn't have had time to get to c2.

I like these ones more than finding the shortest way to reach a position. Those seem to require too much experimentation because there are so many possible ways to do things. Here it's just a linear deduction.

Actually they can if the Rook moves in a discovered check.

I do believe it's impossible for a king to be checked by two knights or two bishops at the same time however.

2 bishops wont be on the same color... so a king cannot possibly be checked by 2 at the same time. it still wouldnt be possible after a promotion to a bishop either.

Or 2 Queens.

Or 2 Rooks.

Or 2 Pawns.

2 queens is possible.....

@adamplenty: Not quite true!

That looks illegal.

The only last moves could have been g4 and fxg3ep.

So white's b7 bishop is promoted. The promoted pawn must be the f2 pawn.

Black has two promoted pieces, a rook and the d1 bishop. the b7 and c7 pawns have enough white pieces to capture to achieve that. However, that leaves black with only one available piece to capture, a light square bishop.

The only way white's f2 pawn can promote using only one capture, is fxe7. However e7 is a dark square, therefore black's light square bishop cannot be used for that, therefore illegal.