Letter B

1. the second letter of the alphabet.
2. the second highest class of academic mark.
3. Chess denoting the second file from the left, as viewed from White's side of the board.
4. the second constant to appear in an algebraic equation.
5. Geology denoting a soil horizon of intermediate depth, typically the subsoil.
6. the human blood type (in the ABO system) containing the B antigen and lacking the A.
7. Music the seventh note of the diatonic scale of C major.
8. a key based on a scale with B as its keynote.
9. the chemical element boron.
10. Physics magnetic flux density.