104. Assign oxidation number of the underlined elements in each of the following species:

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Let the oxidation number of S = x
Writing the oxidation number of each atom at the top of its symbol.
 +1      -1          x - 2
Na        H            SO₄ 
Sum of the oxidation number of various atoms = 0
                        +1 + 1 + x + 4(-2) = 0
                                       x - 6 = 0
or                                      x = +6
 Oxidation number of S in NaHSO₄ = +6