25. Which of the following anions is the strongest base?
(A)
(B)
(C)
(D)
(E)

21. _____is the upward force exerted on an object in a gaseous or liquid fluid. The mass measured by an analytical balance in air is _____ its actual mass. (A) Buoyancy; heavier than (B) Buoyancy; lighter than (C) Electromagnetic force; heavier than (D) Electromagnetic force; lighter than (E) Tare; equal to

22. How many electrons in an atom can have the quantum numbers n = 4, 1 = 2? (A) 18 (B) 32 (C) 2 (D) 6 (E) 10

23. Which of the following options shows the molecules in the order from most polar to least polar? ("=" indicates that two molecules are similarly polar) (A) CF2Cl2 ＞ CF2H2 ＞ CCl2H2 ＞ CH4 = CCl4 (B) CF2H2 ＞ CCl2H2 ＞ CF2Cl2 ＞ CH4 = CCl4 (C) CH4＞ CF2Cl2 ＞ CF2H2 ＞ CCl4 ＞ CCl2H2 (D) CF2Cl2 ＞ CF2H2 ＞ CCl4 ＞ CCl2H2 ＞ CH4 (E) CH4 ＞ CF2H2 ＞ CF2Cl2 ＞ CCl4 ＞ CCl2H2

24. Lead(II) nitrate reacts with sodium chloride in aqueous solution to form a precipitate. What is the net ionic equation for the precipitation process? (A)(B)(C) (D)(E)

26. Polystyrene is an addition polymer of styrene. What would be the effect, if some divinylbenzene were added to styrene and then polymerized? (A) The polymer would be more flexible. Divinylbenzene acts as a plasticizer. (B) The polymer would be less flammable than pure polystyrene. (C) There would be an effect, but it cannot be predicted. (D) There would be no effect on the properties of the polymer. (E) Divinylbenzene would act as a cross-linking agent, making the polymer stronger.

27. Which of the following quantum model is most adequate as an approximation to describe an t-electron moving in ẞ-carotene? (A) a particle in a one-dimensional box (B) harmonic oscillator (C) a freely moving particle (D) rotation in two dimensions (E) a rigid rotor

28. Consider the reaction 2NO2(g) → 2NO(g) + O2(g). The concentration of NO2 was measured to be 0.0038 mol/L after 200 s and 0.0033 mol/L after 250 s. Calculate the reaction rate for NO2. (A) (B)(C) (D)(E)

29. A liquid above the packed solid following a centrifugation is called the _____(A) solvonatant (B) analyte (C) serum (D) decanted (E) supernatant

30. Which of the options below shows an INCORRECT chemical formula for the named compound? (A) iron(II) oxide FeO (B) potassium sulfate K2SO4 (C) sodium sulfide NaS (D) zinc nitrate Zn(NO3)2 (E) calcium carbonate CaCO3

31. During the heart's beating process, the activity of cardiomyocytes generates a magnetic field in space. In 1963, Baule and others first recorded the magnetic field generated by the electrical currents in the human heart, leading to the development of magnetocardiography (MCG). Using the Biot-Savart law to estimate the magnetic field. Suppose that I = A is the total current generated by myocardial activity and r = 0.1 m is the distance to the measurement point, what is the order of magnitude of the magnetic field generated by the heart in T? The permeability of free space is µ0=1.26× (T·m/A). (A)T (B) T (C) T (D)T (E) T