4 Duck the first diamond completely—10. Finesse the 10 of diamonds—6. Play to drop the jack of diamonds—2.
Thanks to the heart opening, you have four tricks outside of diamonds and you need only five diamond tricks. Finessing the 10 of diamonds is better than playing for a 3-2 split (or a singleton jack), since it guards against any 4-1 break and may bring in the entire suit. But you have an absolutely sure play by ducking the trick completely—if West has all five missing diamonds, you will still be able to win five tricks by finessing the 10 on the second lead of the suit, whereas if you finesse the 10 at once, you can bring home only four. My generous two-point award for the play for the drop is in grudging recognition of the fact that most of the time superior skill will not be necessary on a hand like this one.
5 Win the club ace, lead to a high heart and take a spade finesse—10. Win the dub ace, cash one high spade, play hearts, discarding the club queen, then take the spade finesse—5. Proceed as above but without cashing a high spade first—1.
The situation is different from that in Question 2. Here, you have only two trumps in dummy, and if you cash a top trump first, guarding against a singleton queen in the West hand, you will be unable to take a second finesse and pick up four to the queen in the East hand—a holding that is far more likely (the odds are about 4 to 1) than West's having the lone queen. To succeed against this distribution, you must leave a second entry to dummy; hence cashing all of the hearts in order to take an immediate discard receives credit only because it may not be necessary to finesse twice in the trump suit. Finally, one spade finesse is better than trying to drop a doubleton queen; thus the one-point award.
6 After taking the club ace, lead the heart 10 and let it run unless covered; if it loses, cash a high heart to see if it is necessary to repeat the finesse—10. Cash the heart ace (or king), then go to dummy with a spade and run the heart 10 if it is not covered—8. Cash a top heart but then lead a low heart to the second round of trumps—7. Cash the top hearts, then run diamonds—2.
The only real danger is that trumps may not split. The top-rated play preserves chances to make the contract against East's having all five of the missing hearts. The second choice guards against his holding four to the queen-jack. The third plan gets a slightly reduced award because although it succeeds as far as the trump suit is concerned, it needlessly increases the risk of a diamond ruff. As for the fourth award, cashing two top hearts is superior to taking two heart finesses or attempting to ruff clubs at once.
7 Win the ace of hearts, draw trumps, ruff your third diamond, then lead the 8 of hearts—10. Take the heart finesse at the first trick; if it loses, finesse against West for the queen of clubs—2.
Overtricks are not important, so by refusing the heart finesse and playing as first described, you will make the contract against every possible distribution. Whoever eventually wins the second heart trick with the king will have to lead clubs or give you a ruff and discard. Taking two finesses is worth far less than playing the sure thing, but I am awarding two points because the heart finesse might win, and because I have arbitrarily given West the queen of clubs and you guessed right.
8 After winning the heart ace, cash the king and ace of diamonds, then finesse in spades if necessary—10. Cash the ace and king of spades, then if necessary cash the diamond king and finesse the diamond 9—6. Cash the diamond king, then finesse against East for the diamond queen—1.
On the face of it, making your contract depends upon guessing which finesse will succeed. But you can give yourself an extra chance by trying to drop a queen in one suit before committing yourself to a finesse in the other. With eight cards in diamonds and only seven in spades, there is a much better chance of dropping the doubleton queen of diamonds. The final one-point award is for taking the diamond finesse the proper way—by first cashing the king to perhaps drop a singleton queen in West's hand without losing the chance to pick up four to the queen in East's hand.