In [PtCl(NO2)(NH3)4]SO4 the oxidation number is?

To determine the oxidation number of Pt in [PtCl(NO2)(NH3)4]SO4, we need to consider the overall charge of the complex ion.

The overall charge of the complex ion is 2- (since SO4 has a charge of 2-). The sum of the oxidation numbers in a neutral compound is always zero. Since the overall charge of the complex ion is 2-, the sum of the oxidation numbers of all the elements in the complex ion must be equal to -2.

Let x be the oxidation number of Pt, -1 be the oxidation number of Cl, +3 be the oxidation number of N in NO2, and +1 be the oxidation number of N in NH3.

The sum of the oxidation numbers is:
x + (-1) + 2(+3) + 4(+1) = -2
x - 1 + 6 + 4 = -2
x + 9 = -2
x = -2 - 9
x = -11

Therefore, the oxidation number of Pt in [PtCl(NO2)(NH3)4]SO4 is -11.

+4