Redox Reactions...

Which is the anhydride of $${HNO}_{3}$$ out of $${N}_{2}O,NO,{N}_{2}{O}_{5}$$?

$${ VO }_{ 2 }^{ 2+ }$$ and $${ VO }^{ 2+ }$$ are known as vanadyl ion. The oxidation number of vanadium in each ions are, respectively :

Which of the following is a spectator ion in the reaction?
$$2Na+2HCl \rightarrow 2NaCl + H_2$$

Oxidation number of carbon and total number of atoms in carbon suboxide are :

Which ordering of compounds is according to the decreasing order of the oxidation state of nitrogen?

Which one of the following is not correct for the reaction?
$$(CN)_2 + H_2O \rightarrow HCN+ HOCN$$

$${ K }_{ 3 }Cr{ \left( { O }_{ 2 } \right)  }_{ x }$$ has peroxy linkage with oxidation number of $$Cr$$ as $$+5$$. The value of $$x$$ is :

Which has maximum oxidation number of the underlined atom in the following?