[填空题]
The equation below shows the reaction between concentrated s a c2d(ibtt btbs),5r;ulfuric acid a p:ckd)1x w :symoi20 5ceeyh2nd potd22o x5 y:ice 0wsy1m k)pe:hcassium iodide.
$8KI(s) + 5H_2SO_4(aq) \rightarrow 4K_2SO_4(aq) + 4l2(g) + H_2S(g) + 4H_2O(l)$
1.State the oxidation state of sulfur in $H_2SO_4$ and $4H_2S$.In $H_2SO_4$, x= , in $4H_2S$, x=
2.Write the half equations for the oxidation and reduction reactions.
3.Define oxidizing agent in terms of electrons.
4.Identify the oxidizing agent in the equation.