question_answer 1)

  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:

  (a) Oxidation state of hydrogen may be \[+1\] or \[-1\overset{+1-1}{\mathop{HCl}}\,,\overset{+1-1}{\mathop{NaH}}\,\]