The correct order of melting points of hydrides of group 16 elements is :

Consider the following reaction :

A + alkali $$\to$$ B (Major Product)

If B is an oxoacid of phosphorus with no P-H bond, then A is :

The number of bridged oxygen atoms present in compound B formed from the following reactions is

Pb(NO₃)₂ $$\buildrel {673\,K} \over \longrightarrow $$ A + PbO + O₂

A $$\buildrel {Dimerise} \over \longrightarrow $$ B

White precipitate of AgCl dissolves in aqueous ammonia solution due to formation of :