Puzzle of the week #82

Level: 
5-Queen
Chess Diagram: 

------k-
pp---pp-
----pn-P
----Nq--
--P-----
-----Q--
PP-r-P--
K------R

America and the World have a new chess wonder, the 14 years old Ray Robson from Florida. He already is an International Master at this young age and yesterday he achieved his first GM norm after playing in a very strong tournament called the "Arctic Chess Challenge 2009" from Tromso, Norway. To give a glimpse of his achievement I can mention that in the last round he needed a draw with the Black pieces against the strong Swedish GM Emanuel Berg and he managed to hold that after 74 moves.
Our puzzle is from the game IM Ray Robson - GM Vadim Malakhatko from round 5 and it shows the critical moment in the game when Black was hoping to clarify things on the board: we are at move 30 and he was offering a Queen exchange in the same time as attacking the Knight; on top of this "Ka1" is a bit cramped in the corner. However Ray had other plans and responded with a surprising move: 31.Qxb7! ... Your tasks:
a) How does White win after 31... Qxe5?
b) What is Black's best defence? Explain
Total available points for this puzzle is 20. The answers will be published next week together with puzzle #83.

Puzzle #81 solution:
Jeremy's answer:
"White is up in material by a Knight in a Queen endgame but it is very hard to win. One good thing though is that Black's King is on the side of the board so that it is easy for White to mate. Another good thing for White is that Black Queen is not really doing anything in the corner there.
1.Qe7+ Kg6 Any other King move by Black allows checkmate for White.
2.Nf8+! ... Instead of having another Queen check, this check draws Black's King closer to White's King where it can help the other pieces form a mating net.
2... Kf5 The other legal moves lead to a fork with the Knight.
3. Qh7+! Kf4 (After any other moves such as 3...Ke5 of Kf6, 4.Nd7+ ... wins the Queen.)
4.Qd3! ... The Black Queen has no checks while White threatens Ng6#. Black has to sacrifice his Queen to stop checkmate.
4... Qxf8 5.Qf1+ ... wins the Queen 4... Qb6 5.Ng6+ Qxg6 6.Qxg6 ... 1-0
Andy Q's answer:
"One element used in the solution is forking. White puts Black in a position where his Queen will be forked. Another element White uses is skewering. If Black takes the Knight on f8 at move #4, White uses his Queen to skewer Black on f1 and Black loses his Queen."

Correct solutions:
Jeremy - 14 points
Andy Q - 13 points
Owen - 4 points
Alex Ge - 2 points
Wilson - 1 point

STANDINGS

Andy Q - 103 points
Rick - 77 points
Joshua - 71 points
Karl, Wilson, Alex Ge, Jeremy - 39 points
James - 23 points
Katerina, Andy Y - 20 points
Marcus - 19 points
Nathaniel - 18 points
Owen - 14 points

Comment: 

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