Give an example to show the effect of concentration of nitric acid on theformation of oxidation product.

Nitric acid forms an oxide of nitrogen on reaction with P₄O₁₀. Write the reaction involved. Also write the resonating structures of the oxide of nitrogen formed.

Phosphorus has three allotropic forms — (i) white phosphorus (ii) red phosphorus and (iii) black phosphorus. Write the difference between white and red phosphorus on the basis of their structure and reactivity.

PCl₅ reacts with finely divided silver on heating and a white silver salt is obtained, which dissolves on adding excess aqueous NH₃ solution. Write the reactions involved to explain what happens.

Phosphorus forms a number of oxoacids. Out of these oxoacidsphosphinicacid has strong reducing property. Write its structure and also write a reaction showing its reducing behaviour.