LEARNING CENTER

Q. We lead the top of an honor sequence in notrump contracts. Yes, it needs to be a 3-card sequence, but we consider three cards with one missing (here: QJ9) to be a sequence as well. 

8. When in third seat, we play the lowest card necessary to win the trick. Since dummy has the 10, our 8, 9, J and Q are equivalent honors here. Playing the Q would deny the J which we don't want to do. 

9. This is now a signaling situation since we can not win the trick. When signaling (standard signals), you want to be as clear as possible. We do not want to signal with a potential trick, which is why we don't signal with the Q or J (potentially setting up the 10). 

Q (or J). You should "split" your honors to ensure that your side takes a diamond trick. Maybe declarer has K10x and is hoping to sneak one past you. Whether you split high (the Q) or low (the J) is a style choice. 

Anything but the 2. We want East to continue diamonds. If you play the 2, East is sure to switch if they play 4th best leads, since West will be known to have only four cards in diamonds (no lower cards out). If you play any other card (we could debate what the technically correct falsecard is), East might continue diamonds. Hiding the 2 is a frequent theme as declarer to make life more difficult for the defense.