Identify the process in which change in the oxidation state is five:

The oxidation number of phosphorus in ATP (adenosine triphosphate) is :

Reaction of Grignard reagent, C?H?MgBr with C?H?O followed by hydrolysis gives compound "A” which reacts instantly with Lucas reagent to give compound B, C??H??Cl. The compound B is:
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On heating, lead (II) nitrate gives a brown gas (A). The gas (A) on cooling changes to a colourless solid/liquid (B). (B) on heating with NO changes to a blue solid (C). The oxidation number of nitrogen in solid (C) is:

Oxidation number of potassium in ${\mathrm{K}}_2\mathrm{O},{\mathrm{K}}_2{\mathrm{O}}_2$ ${}_{}{}_{}{}_{}$ and ${\mathrm{K}\mathrm{O}}_2$ ${}_{}$ respectively is