MCAT General Chemistry Question 189: Answer and Explanation

Home > MCAT Test > MCAT general chemistry practice tests

Test Information

Question: 189

9. Based on the reaction mechanism shown below, which of the following statements is correct?

2 NO + O2 → 2 NO2

1) 2 NO → N2O2 (fast)

2) N2O2 + O2 → 2 NO2 (slow)

  • A. from left to right, because the decrease in electronegativity would make it easier to lose electrons.
  • B. from left to right, because the decrease in atomic radius would result in more stable positive ions.
  • C. from right to left, because the decrease in ionization energy would make it easier to lose electrons.
  • D. from right to left, because the decrease in electron affinity would result in more stable positive ions.

Correct Answer: C

Explanation:

C Choice A is eliminated because electronegativity increases from left to right on the periodic table. Choice B is eliminated because the stability of positive ions increases as you go up and to the left on the periodic table. Finally, choice D is eliminated since electron affinity is the energy released upon gaining an electron and does not relate to the stability of a positive ion. Choice C is the correct answer because ionization energy, or the energy required to remove an electron, decreases from right to left due to a decrease in effective nuclear charge.

Previous       Next