Asked in PMC Practice Test 10 (2021) 2021Moderate

Number of valence electrons in Cl- Ion are?

Correct answer: D. 8

  • A. 18
  • B. 10
  • C. 17
  • D. 8

Explanation

Option A: This option suggests that the chloride ion (Cl-) has 18 valence electrons. However, this is incorrect. The correct number of valence electrons for the chloride ion is 8.Option B: This option suggests that the chloride ion (Cl-) has 10 valence electrons. Again, this is incorrect. The correct number of valence electrons for the chloride ion is 8.Option C: This option suggests that the chloride ion (Cl-) has 17 valence electrons. However, this is incorrect. The chloride ion gains an electron to achieve a stable electron configuration, and as a result, it has a different number of valence electrons than the neutral chlorine atom. Option D: This option correctly states that the chloride ion (Cl-) has 8 valence electrons. When chlorine gains one electron to form the chloride ion, it achieves a stable electron configuration with a full outermost energy level, similar to the noble gas argon. The chloride ion has the same electron configuration as argon (2-8-8), which means it has 8 valence electrons.

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