18. Determine Lewis base strength in the gas phase of following amines:
(A) NMe₃ ＞ NH₂Me ＞ NH₃
(B) NH₂Me ＞ NMe₃ ＞ NH₃
(C) NH₃ ＞ NMe₃ ＞ NH₂Me
(D) NH₃ ＞ NH₂Me ＞ NMe₃
(E) None of the above.

14. An object is 12 cm in front of a concave spherical mirror, and the image is 3 cm in front of the mirror. What is the focal length of the mirror? (A) 0.25 cm (B) 1.5 cm (C) 2.4 cm (D) 4 cm (E) 13 cm

15. A light from medium A with refractive index (nA) enters medium B and medium C with refractive index, nB and nC respectively. Which of the followings is correct?(A) nA ＞ nB ＞ nC (B) nA ＞ nC ＞ nB (C) nB ＞ nC ＞ nA (D) nB ＞ nA ＞ nC (E) nC ＞ nA ＞ nB

16. Complete the following nuclear reaction:The □ , A and B should be: (A) He, 249 and 86 (B) C, 244 and 98 (C) C, 249 and 92 (D) C, 249 and 98 (E) He, 244 and 98

17. An anion has the following Lewis structure: What is the possible identity for element E?(A) Si (B) P (C) S (D) Ar (E) Cl

19. Using the data below, calculate the normal boiling point of liquid A at 1 atm, A(liquid) → A(gas): the ΔH° = 25.0 kJ/mol and the ΔS° = 50.0 JK−1mol−1 (A) 50 K (B) 200 K (C) 227 K (D) 323 K (E) 500 K

20. Which of the followings octahedral complexes will not form precipitate of AgI at once after the aqueous AgNO3 is added? (A) Co(NH3)6I3 (B) Pt(NH3)4I4 (C) Na2PtI6 (D) Cr(NH3)4I3 (E) All of them will form AgI precipitate.

21. How to make a p-type semiconductor? (A) Dope host atoms (Si) with atoms having fewer valence electrons than the host, such as B. (B) Dope host atoms (As) with atoms having fewer valence electrons than the host, such as Se. (C) Dope host atoms (Si) with atoms having more valence electrons than the host, such as As. (D) Dope host atoms (As) with atoms having more valence electrons than the host, such as Ge. (E) None of the above.

22. Based on reaction shown as below, the two complexes can be classified into which type of isomerism? (A) stereoisomerism (B) optical isomerism (C) geometric isomerism (D) ionization isomerism (E) linkage isomerism

23. What is the product called after glycine and alanine undergo condensation reactions? (A) ester (B) dipeptide (C) DNA (D) polysaccharides (E) None of the above.

24. Which compound does not possess a sp2 hybridized orbital? (A) 2-butanone (B) aspirin (C) acetic anhydride (D) 2-propanol (E) aniline