In which of the following compound central atom has +4 oxidation state?

The correct answer is H₂SO₃.

To determine the oxidation state of the central sulfur atom ($S$) in sulfurous acid ($H_{2}S{O}_3$), we use the standard oxidation state rules:
1. The oxidation state of Hydrogen ($H$) is generally $+1$ when bonded to non-metals.
2. The oxidation state of Oxygen ($O$) is generally $-2$ in most of its compounds.
3. The sum of the oxidation states of all atoms in a neutral compound must equal $0$.

Let the oxidation state of the central sulfur atom ($S$) be represented by $x$.

Setting up the equation for the neutral molecule $H_{2}S{O}_3$:

$2\times (+1)+x+3\times (-2)=0$

Simplifying the expression:

$2+x-6=0$

$x-4=0$

$x=+4$

Therefore, the oxidation state of the central sulfur atom in H₂SO₃ is indeed +4.