Chemistry exam three

41. A student is interested in determining the content of a leaf from his/her environment and performed the following.

Step 1: He/she dried the leaves up in sun light
Step 2: Evaluated the work and draw conclusions
Step 3: Collected leaves from the tree around his village
Step 4: He/she boiled the leaves and collected the leaves extracted
Step 5: Analyze the content of the leaves extracted using an instrument

Which of the following is the CORRECT procedure if a student developed an experimental skill?

A. Steps: 3 → 1 → 5 → 4 → 2 B. Steps: 3 → 1 → 4 → 5 → 2 C. Steps: 3 → 4 → 1 → 5 → 2 D. Steps: 3 → 5 → 4 → 1 → 2

42. Which of the following characteristics of an electromagnetic radiation is CORRECT?

A. The wave length of an electromagnetic radiation is directly proportional to its frequency. B. The speed of an electromagnetic wave is independent of the nature of the medium it travels through. C. The speed of an electromagnetic radiation increases with increase in its frequency. D. The speed of an electromagnetic radiation decreases with increase in its wavelength.

43. "The hydrogen atom moves in a fixed circular orbit associated with allowable energy states". This is called _____.

A. Aufbau's principle B. Pauli's principle C. Bohr's theory D. Planck's theory

44. Which of the following is the core electron configuration of the metal ion in ferric sulfate, Fe₂(SO₄)₃? (Atomic Number of Fe = 26)

A. [Ar] 3d⁶ B. [Ar] 3d⁵ C. [Ar] 4s²3d⁶ D. [Ar] 4s²3d⁵

45. A chemical bond that results from the attractive force between shared electrons and nonmetal nucleus is called _____.

A. metallic bond B. hydrogen bond C. ionic bond D. covalent bond

46. From the assumption of kinetic molecular theory of gases, which of the following is CORRECT?

A. The average kinetic energy of gas particles is inversely proportional to the absolute temperature of the gas. B. The pressure of a gas is the effect of the negligible volume of the gas compared to the total volume of the gas. C. Under ordinary conditions, the total volume of gas molecules is much smaller than the total volume of gas. D. There are some forces of attraction or repulsion between gas particles.

47. Which of the following is CORRECT about the phase change observed in water?

A. When a solid ice is heated, it is changed to liquid water without melting. B. Water starts to evaporate at the boiling point and condenses at the melting point. C. At the melting point of ice, the temperature remains constant. D. At the boiling point temperature, water exists in three different physical states.

48. Given the symbols of the three subatomic particles: electrons (e^-), protons (p⁺) and neutrons (n⁰), which of the following is the CORRECT comparison of the absolute masses of protons, electrons and neutrons?

A. Mass of e^- = mass of p⁺ > mass of n⁰ B. Mass of e^- > mass of p⁺ = mass of n⁰ C. Mass of e^- > mass of p⁺ > mass of n⁰ D. Mass of e^- < mass of p⁺ < mass of n⁰

49. In the modern periodic table, what is the name of the group that contains the most electronegative elements?

A. Halogens B. Alkali C. Noble gases D. Chalcogens

50. A given element has atomic number of 55 and mass number of 133. Which of the following describes CORRECTLY the property of this element?

A. The metallic character of the element is high. B. The non-metallic character of the element is high. C. The element has high electronegativity. D. The element has high electron affinity.

51. Which of the following is a Lewis acid?

A. SO₃^2- B. SO₄^2- C. NH₃ D. BF₃

52. The pH of a 0.10 M solution of an aqueous solution of a certain acid is 3. What is the value of acid ionization constant (Ka) of this acid?

A. 1.0 x 10^-5 B. 1.0 x 10^-7 C. 1.0 x 10^-4 D. 1.0 x 10^-3

53. The shift in the position of equilibrium caused by the addition of an ion already involved in the reaction is known as __________.

A. buffer - ion effect B. common - ion effect C. titration - effect D. hydrolysis - effect

54. Which of the following is CORRECT about equivalents of acids and bases?

A. The number of moles of an acid or base required to form a one molar aqueous acidic or basic solution. B. The volume of an acid or base required to reach equivalence point during acid - base titration reaction. C. It is the amount of a substance that is required to react with one mole of hydrogen ions in acid - base reactions. D. It is the amount of a substance that is required to react with one mole of hydroxide ions in redox reactions.

55. A 250 mL solution is formed from 24.5 g of sulfuric acid (H₂SO₄). What is the normality of this solution? (Mt. wt. H₂SO₄ = 98 g/mol)

A. 2.00 N B. 4.00 N C. 0.125 N D. 0.250 N

56. Consider the mechanism for the decomposition of N₂O₅ to NO₂:

First step: 2N₂O₅ (g) ⇌ 2N₄O₁₀(g) (fast)
Second step: N₄O₁₀(g) → N₂O₃(g) + 2NO₂(g) + O₃(g) (slow)
Third step: N₂O₃ (g) + O₃ (g) → 2 NO₂(g) + O₂(g) (fast)
Overall: 2N₂O₅ (g) → 4 NO₂(g) + O₂(g)

Which step is the rate - determining step?

A. Second step B. The overall step C. First step D. Third step

57. Consider the following reaction:
N₂(g) + O₂(g) ⇌ 2NO (g)
The equilibrium concentrations of gaseous nitrogen, oxygen and nitrogen monoxide in a sealed container are as follows: [N₂] = 1 x 10^-5 M, [O₂] = 2 x 10^-5 M and [NO] = 4 x 10^-5 M. What is the equilibrium constant for the reaction?

A. 4 B. 16 C. 2 D. 8

58. At a certain temperature the following reaction has an equilibrium constant Kc = 12.4.
N₂(g) + 3H₂(g) ⇌ 2NH₃(g)
If [N₂] = 2.0 M, [H₂] = 2.0 M and [NH₃] = 10.0 M, to which direction will the reaction proceed to reach equilibrium?

A. The reaction will proceed to the forward direction. B. The equilibrium is independent of the concentration. C. The reaction is at a chemical equilibrium. D. The reaction will proceed to the reverse direction.

59. Which of the following is the general formula for saturated monocarboxylic acids? (R is an alkyl group)

A. R-COOH B. R-COOR C. R-COR D. R-CHO

60. Upon standing long, "Tella" or "Tej" turns sour. Which of the following is the CORRECT explanation for the observed effect?

A. Decomposition reaction of alcohol. B. Addition reaction of alcohol with an acid. C. The oxidation of alcohol to an acid. D. The reduction of alcohol to an acid.

Chemistry Exam Three

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