WAEC Chemistry 2025 Objective — Question 36
Question 36 of 50 from the West African Examinations Council (WAEC) Chemistry 2025 Objective paper, with the correct answer and a full explanation.
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The electron configuration of element Y is 1s2 2s2 2p6 3s2 3p4; therefore Y
- A. has a mass number of 16
- B. has three unpaired electrons
- C. belongs to period 4
- D. belongs to group VICorrect
Explanation
The electron configuration 1s2 2s2 2p6 3s2 3p4 corresponds to sulphur (S), which is in group VI of the periodic table. The number of electrons in the orbitals with the highest principal quantum number (3s2 3p4) indicates it is in period 3 and group VI; the mass number is 32 (not 16) and it has two unpaired electrons, not three.
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