21. Specify the number of unpaired electrons in CoF₆ ^3– (F– ion is a weak field ligand).
(A) 0
(B) 1
(C) 2
(D) 4
(E) 5

17. For a heterogeneous catalyzed reaction, the reaction can be divided into four processes: I. Escape or desorption of the products.II. Reaction of the adsorbed reactants.III. Migration of the adsorbed reactants on the surface of the catalyst.IV. Adsorption and activation of the reactants.What is the correct order of the process? (A) I → II →  III →  IV (B) IV →  III →  II →  I (C) I →  IV →  II→  III (D) IV →  II→  III → I (E) III →  II →  I →  IV

複選題18. The band gap of the semiconductor aluminum phosphide (AlP) is 2.5 eV. What color of light is emitted by AlP diode? (1 eV = 1.6 × 10-19 J； Planck’s constant: 6.626 × 10-34 J·s = 4.136 × 10-15 eV·s) (A) red (B) orange (C) yellow (D) green (E) blue

19. Which radiation is applied in nuclear magnetic resonance (NMR) technique? (A) X-ray (B) ultraviolet (C) infrared (D) visible (E) radio wave

20. Which of the following reactions is a disproportionation reaction? (A) HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) (B) Cl2(aq) + 2I⁻(aq) → I2(aq) + 2Cl⁻(aq) (C) CaSiO3(s) + 8HF(aq) → H2SiF6(aq) + CaF2(aq) + 3H2O(l) (D) AgNO3(aq) + NaCl(aq) → AgCl(aq) + NaNO3(aq) (E) Cl2(aq) + 2NaOH(aq) → NaClO(aq) + NaCl(aq) + H2O(l)

22. The MnO4ˉ ion is often used to analyze the Fe2+ concentration in an aqueous solution, based on the reaction in acidic condition as follows: (MnO4ˉ + Fe2+ ―→ Fe3+ + Mn2+ ) A 50.00 mL sample of a solution containing Fe2+ requires 40.00 mL of a 0.025 M KMnO4 solution for complete reaction. What is the concentration of the Fe2+ in the original solution? (A) 1.0 × 10-1 M (B) 1.8 × 10-2 M (C) 4.5 × 10-3 M (D) 1.8 × 10-3 M (E) 9.1 × 10-4 M

23. What is the number of lone pairs of electrons in the NO2 – ion? (A) 4 (B) 5 (C) 6 (D) 7 (E) 8

24. If you add 0.10 M silver nitrate dropwise to a solution consisting of 0.10 M Cl– and 0.10 M CrO4 2–, the precipitates are obtained. Given the Ksp for Ag2CrO4 is 9.0 × 10–12 and that for AgCl is 1.6 × 10–10. Which of the followings will precipitate first? (A) silver chloride (B) silver chromate (C) silver nitrate (D) It cannot be determined by the information given. (E) silver metal

25. When the Pd-106 nucleus is struck with an alpha particle, a proton is produced along with a new element. What is this new element? (A) Cd-112 (B) Cd-109 (C) Ag-108 (D) Ag-109 (E) Ag-110

26. How many unpaired electrons are present in the F2 2+ ion? The order of the molecular orbitals is (σ2s)(σ2s*)(σ2p)(π2p)(π2p*)(σ2p*). (A) 0 (B) 1 (C) 2 (D) 3 (E) 4

27. You are holding four identical balloons each containing 10.0 g of a different gas. The balloon containing which gas is the largest balloon? (A) H2 (B) He (C) Ne (D) O2 (E) All balloons have the same volume.