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

Answer: (A)

The oxidation number of hydrogen is always + 1

Answer 2

: Oxidation number of hydrogen may be + 1 or – 1 or 0. For example, in HX it is +1, in hydrides (MH) it is -1 and in $H_{2}$ it is 0.