WAEC Chemistry 2019 Objective — Question 46

Question 46 of 50 from the West African Examinations Council (WAEC) Chemistry 2019 Objective paper, with the correct answer and a full explanation.

The number of electrons in the 3d orbital of 24Cr is

A. 2
B. 3
C. 4
D. 5Correct

Explanation

Chromium is an exception to the normal filling order: its actual configuration is 1s²2s²2p⁶3s²3p⁶4s¹3d⁵ (not 3d⁴), giving 5 electrons in the 3d orbital.

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