Instructions: Cover the Answer Key and fill in each blank.

1. Diborane ($B_{2}H_{6}$) has _____ bridging hydrogen atoms.
2. The bridging B-H-B bonds in $B_{2}H_{6}$ are called _____ bonds.
3. Each bridging bond in $B_{2}H_{6}$ is a -centre--electron bond.
4. The formula of borax is _____.
5. Borax contains _____ $BO_{3}$ units and _____ $BO_{4}$ units.
6. Boric acid (H_{3}$$BO_{3}) acts as a _____ acid by accepting _____ from water.
7. H_{3}$$BO_{3} is _____ basic (mono/di/tri).
8. $AlCl_{3}$ dimerises to form _____, acting as a _____ acid.
9. The _____ effect makes Tl prefer the +1 oxidation state.
10. The hybridization of carbon in diamond is _____.
11. The hybridization of carbon in graphite is _____.
12. CO binds haemoglobin approximately _____ times more strongly than $O_{2}$.
13. The bond dissociation energy of $N_{2}$ is approximately _____ kJ/mol.
14. The Haber process conditions are: catalyst = _____, temperature = _____°C, pressure = _____ atm.
15. In the Ostwald process, Step 1 catalyst is _____ at _____°C.
16. In the Ostwald process, Step 2 (2NO + $O_{2}$ → 2N$O_{2}$) requires _____ catalyst.
17. The anhydride of $HNO_{3}$ is _____.
18. The anhydride of HN$O_{2}$ is _____.
19. $N_{2}$O is called _____ gas and has N in _____ oxidation state.
20. The two neutral nitrogen oxides are _____ and _____.
21. N$O_{2}$ dimerises to form the colourless compound _____.
22. The three allotropes of phosphorus are _____, _____, and _____.
23. The most stable allotrope of phosphorus is _____.
24. $PCl_{5}$ has _____ geometry and _____ hybridization.
25. In $PCl_{5}$, the _____ bonds are longer than the _____ bonds.
26. The basicity of $H_{3}$P$O_{2}$ is determined by counting _____ bonds.
27. $H_{3}$P$O_{2}$ has _____ P-OH bond(s), making it _____ basic.
28. H_{3}$$PO_{3} has _____ P-OH bond(s), making it _____ basic.
29. H_{3}$$PO_{4} has _____ P-OH bond(s), making it _____ basic.
30. The reaction 2Mg + C$O_{2}$ → _____ shows Mg is a stronger _____ than C$O_{2}$.

--- ANSWER KEY ---

1. 2 | 2. Banana bonds | 3. 3-centre-2-electron | 4. $Na_{2}B_{4}O_{7}$·$10H_{2}O$ | 5. Two $BO_{3}$, Two $BO_{4}$
2. Lewis acid; $OH^{-}$ | 7. Monobasic | 8. $Al_{2}Cl_{6}$; Lewis | 9. Inert pair | 10. $sp^{3}$
3. $sp^{2}$ | 12. 200 | 13. 945 | 14. Fe; 450; 200 | 15. Pt-Rh gauze; 500
4. No | 17. N_{2}$$O_{5} | 18. N_{2}$$O_{3} | 19. Laughing; +1 | 20. $N_{2}$O and NO
5. N_{2}$$O_{4} | 22. White, Red, Black | 23. Black phosphorus | 24. Trigonal bipyramidal; $sp^{3}$d | 25. Axial; equatorial
6. P-OH | 27. One; mono | 28. Two; di | 29. Three; tri | 30. 2MgO + C; reducing agent