13. The flux of the electric fieldN/C through a 2 m² portion of the xz plane is ______.
(A) 16 N●m² /C
(B) −48 N●m² /C
(C) 48 N●m² /C
(D) −60 N●m² /C
(E) 60 N●m² /C

9. A gas in a cylinder starts from initial state i to finial state f through 4 different paths as shown in the figure. Regarding to the heat energy, work, and internal energy, which statements is incorrect?(A) Path 1 is isobaric expansion, gas must be heated. (B) Path 2 is isothermal expansion； no work is involved in this process. (C) Path 3 is adiabatic expansion, therefore no heat transfer occurred. (D) Path 4 is isochoric cooling； heat is extracted out of gas. (E) Gas do not do work for path 4 only.

10. A resistor of unknown resistance and a 15 Ω resistor are connected across a 20 V emf in such a way that a 2 A current is observed. What is the value of the unknown resistance? (A) 5 Ω (B) 7.5 Ω (C) 12 Ω (D) 30 Ω (E) 75 Ω

11. A conducting sphere of radius R contains a positive charge. Which figure correctly represents the magnitude of the electric field E as a function of the distance r from the center of the sphere? (A) (B)(C)(D)(E)

12. Which equation is not one of Maxwell’s equations? (A) (B) (C) (D) (E)

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

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.

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