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.

Name three oxoacids of nitrogen. Write the disproportionation reaction of that oxoacid of nitrogen in which nitrogen is in +3 oxidation state.

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.

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

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.