MCAT General Chemistry Question 1: Answer and Explanation

Home > MCAT Test > MCAT general chemistry practice tests

Test Information

Question: 1

1. Which of the following is the correct electron configuration for Zn2+?

  • A. 1s22s22p63s23p64s03d10
  • B. 1s22s22p63s23p64s23d8
  • C. 1s22s22p63s23p64s23d10
  • D. 1s22s22p63s23p64s03d8

Correct Answer: A

Explanation:

Remember that when electrons are removed from an element, forming a cation, they will be removed from the subshell with the highest n value first. Zn0 has 30 electrons, so it would have an electron configuration of 1s22s22p63s23p64s23d10. The 4s subshell has the highest principal quantum number, so it is emptied first, forming 1s22s22p63s23p64s03d10. Choice (B) implies that electrons are pulled out of the d orbital, choice (C) presents the configuration of the uncharged zinc atom, and choice (D) shows the configuration that would exist if four electrons were removed.

       Next