12. Which of the following statements is(are) true?
I. An excited atom can return to its ground state by absorbing electromagnetic radiation. 

Ⅱ.energy of an atom is increased when electromagnetic radiation is emi 

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) II, III, IV
(B) III, V
(C) I, II, III
(D) III, IV, V
(E) I, II, IV

8. Which of the following oxides is amphoteric? (A) BeO (B) MgO(C) CaO(D) SrO (E) BaO

9. At 760 K, acetaldehyde decomposes to carbon monoxide and methane:CH3CHO→CH4 + COA plot of In [CH3CHO] versus time is linear. After 530 s, [CH3CHO] decreases to one half of its initial value of 0.10 M.What is the rate law for the reaction? (A)(B)(C)(D) (E)

10. Consider the reaction3A+B+C→D+Ewhere the rate law is defined as   An experiment is carried out where [B]0 = [C]0 = 1.00 M and [A]0 = 2.72 x 10-4 M. What is the half-life for this experiment? (A) 8.19 x 10-7s (B) 1.36 x 10-5s (C) 4.17 x 10-3s (D) 2.21 x 101s (E) 1.66 x 102s

11. The rate law for a reaction is found to be Rate = K[A]2[B]. Which of the following mechanisms gives this rate law?  (A) I only (B) II only (C) III (D) I and Il (E) II and III

13. An electron in a one-dimensional box requires energy with wavelength 8080 nm to excite it from the n = 2 energy level to the n = 3 energy level. Calculate the length of the box. (A) 1.00 nm (B) 1.50 nm (C) 2.50 mm (D) 3.00 gm (E) 3.50 nm

14. The energy expressions for the electrons in the Het ion and the hydrogen atom areEn(H)=-a/n2 and En (He+) =- 4a/n2Which of the following statements is(are) correct?Ⅰ.For the transitions n1→ n2 , the frequency is larger for H than for He+.II. The first ionization energy of the H atom is smaller than the second ionization energy of the He atom.  III. The 1s orbital in He' is larger (in the sense that the probability density is shifted outward) than the is orbital in H. (A) I only (B) II only (C) III only (D) I and II only (E) I, II, and III

15. The wavelength of light associated with the n = 2 to n = 1 electron transition in the hydrogen spectrum is 1.216 x 10-7 m. By what coefficient should this wavelength be multiplied to obtain the wavelength associated with the same electron transition in the Li2+ ion? (A) 1/9 (B) 1/7 (C) 1/4 (D) 1/3 (E) 1

16. A strip of copper is placed in a 1 M solution of copper nitrate, and a strip of silver is placed in a 1 M solution of silver nitrate. The two metal strips are connected to a voltmeter by wires, and a salt bridge connects the solutions. The following standard reduction potentials apply: When the voltmeter is removed and the two electrodes are connected by a wire, which of the following does not take place? (A) Electrons flow in the external circuit from the copper electrode to the silver electrode. (B) The silver electrode increases in mass as the cell operates. (C) There is a net general movement of silver ions through the salt bridge to the copper half-cell. (D) Negative ions pass through the salt bridge from the silver half-cell to the copper half-cell. (E) Some positive copper ions pass through the salt bridge from the copper half-cell to the silver half-cell.

17. The standard potential for the reaction is 0.51 V. What is the equilibrium constant K for this reaction at 250C? (A) 6.3 x 1025 (B) 1.6 x 10-26 (C) 17 (D) -17 (E) 0.015

18. Which of the following is not a valid resonance structure for N3-?(A)(B)(C)(D)(E) All are valid.