Post-UTME Chemistry 2015 Objective — Question 5

Question 5 of 20 from the Post-UTME Screening (Post-UTME) Chemistry 2015 Objective paper, with the correct answer and a full explanation.

The oxidation number of phosphorus in PO4^3- is

A. +1
B. +2
C. +3
D. +5Correct

Explanation

In the phosphate ion PO4^3-, oxygen is -2 (x4=-8); for overall charge -3, P must be +5. (No printed answer key for this session; answer worked out independently.)

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