18. Consider the second-order reaction A → products, Mich has a first half-life of 25 s.If the concentration of A after 15.6 s is 0.36 M, determine the initial concentration of A.
(A) 0.58 M
(B)026M
(C) 0.53 M
(D)0.14M
(E)0.16M

14. See the right figure, there is a metallic sphere, on 的ich a constant electric potential is applied, A chained particle moves fh＞m point A to point B through three different kinds of paths denoted as I, II, and III. Through which path does the particle gain the most electric eneigy?(A) I (B)II (C) III (D) All the same (E) It depends on the sign of the charge.

15. Refer to the figure. A conducting loop (square coil of wire) is pulled at constant velocity through a uniform magnetic field entering the plane. Which of the following statements is correct?(A) Current is induced in the loop in the clockwise direction. (B) Current is induced in the loop in the counterclockwise  direction. (C) Alternating current is induced in the loop.  (D) Charge separation occurs； negative chafes are accumulated at the bottom edge. (E) Charge separation occurs； negative charges are accumulated at the top edge.

16. The coordination geometry of Cr(NO)4 is_____  . (A) tetrahedral (B)trigonal pyramidal (C) see-saw (D) square planar (E) none of tiie above

17. What type of hi^h energy bonds are found in ATP and ADP? (A) ca^oxylic anhydride (B) phosphodiester (C) thioester (D) phosphoanhydride (E) amine

19. Which of the following is the reason for minimum chemical interferences in inductively-coupled plasma? (A) Zeeman efiect correction (B) high ionization efficiency (C) high temperature (D) large number of emission lines (E) none of the above

20. The point group of H2O2 is_______  . (A) C2 (B) C2v (C) C3 (D) C3v(E) none of the above

21. The C–O bond order of CO_ is_______ . (A)1 (B)1.5 (C)2 (D) 2.5 (E) 3

22. The reaction A→B + C is known to be zero order in A with a rate constant of 4.8 x 10-2 mol/L • s at25°C. An experiment was run at 25°C where [A]0 = 4.0 M. What is the concentration of B after 5.0s? (A) 1.7 M (B)4.5 x 10-1 M (C) 3.0 M (D)1.1✖10-1M (E) 2.4 x 10-1 M

23. Which of the following statements is/are true? I. An excited atom can return to its ground state by absorbing electromagnetic radiation. Ⅱ. The ene啊 of an atom is increased when electromagnetic radiation is emitted from it. III. The energy of electromagnetic radiation increases as its frequency increases.IV. An electron in the n = 4 state in the hydrogen atom can go to the n = 2 state by emitting electromagnetic radiation at the appropriate frequency. V. The frequency and wavelength of electromagnetic radiation are inversely proportional to each other. (A) III,v (B)Ⅱ,  III, IV (C) I, Ⅱ, IV (D) I, Ⅱ, III (E)III,IV,V

24. How many electrons can be described by the quantum numbers n = 4, l = 4, ml= 1? (A) 14 (B)6 (C)10 (D)0 (E)2