十分難的chem問題,我相信冇人會識,helpme化學高手

For the 1st question, wikipedia has a very good article to elaborate the rule of oxidation state. Some points are extracted as follows:

Here is the definition of the oxidation state listed by IUPAC:[1]

"Oxidation state :A measure of the degree of oxidation of an atom in a substance. It is defined as the charge an atom might be imagined to have when electrons are counted according to an agreed-upon set of rules:

(1) the oxidation state of a free element (uncombined element) is zero;
(2) for a simple (monatomic) ion, the oxidation state is equal to the net charge on the ion;
(3) hydrogen has an oxidation state of 1 and oxygen has an oxidation state of -2 when they are present in most compounds. (Exceptions to this are that hydrogen has an oxidation state of -1 in hydrides of active metals, e.g. LiH, and oxygen has an oxidation state of -1 in peroxides, e.g. H2O2;
(4) the algebraic sum of oxidation states of all atoms in a neutral molecule must be zero, while in ions the algebraic sum of the oxidation states of the constituent atoms must be equal to the charge on the ion. For example, the oxidation states of sulfur in H2S, S8 (elementary sulfur), SO2, SO3, and H2SO4 are, respectively: -2, 0, +4, +6 and +6. The higher the oxidation state of a given atom, the greater is its degree of oxidation; the lower the oxidation state, the greater is its degree of reduction."

Oxygen has 6 different Oxidation States:

-2 in most oxides. e.g. ZnO, CO2, H20
-1 in all peroxides. e.g. H2O2
-1/2 as in superoxides. e.g. KO2
0 as in O2
+1 in O2F2
+2 in OF2

Thus, H2O2中氧的氧化數是-1,KO2中氧的氧化數是 -0.5

For the 2nd question, 點解酸強度會這樣:HClO4>HClO3>HClO2>HOCl, reference 2 gives a very good explanation:

酸性的递变规律总结如下:

⑴同一元素形成的不同氧化数的含氧酸其酸性以氧化数的递增而增强。
HClO < HClO2 < HClO3 < HClO4
Rn+的电荷数依次增大，Rn+的半径依次减小，根据Φ=Z/r知， Φ增大，R－O的引力增强，导致O－H间的引力依次减弱，酸性则依次增强。

(O2) should be considered as one unit called the superoxide. The oxidation state of superoxide is -1. Superoxide is formed when an oxygen molecule loses one of the electrons from the highest occupied orbital in the oxygen molecule.

al chem有教
H2O2中氧的氧化數是-1KO2中氧的氧化數是否-0.5
一定打錯,H必+1,O的電負性>>H及H只有1e-
ClO4-有4共振
ClO3-3共振
共振多穩定,so酸度強