Question

The oxidation number of an element in a compound is evaluated on the basis of certain rules. Which of the following rules is not correct in this respect ?
A. The oxidation number of hydrogen is always `+1`
B. The algebraic sum of all the oxidation numbers in a compound is zero.
C. An element in the free or the uncombined state bears oxidation number zero.
D. In all its compounds, the oxidation number of fluorine is `-1`.

Answer 1

Correct Answer - A
Oxidation number of hydrogen is always `+1` is a wrong rule since, it is `+1` in hydrogen halides, `-1` in hydrides and zero in `H_(2)` molecules.
All the other three statements (b) , ( c) and (d) are correct.