Among the oxides of nitrogen : N₂O₃, N₂O₄ and N₂O₅; the molecule(s) having nitrogen-nitrogen bond is / are :

In the extraction of copper from its sulphate ore, metal is finally obtained by the oxidation of cuprous sulphide with :

Which of the following conversions involves change in both shape and hybridisation ?

A group 13 element 'X' reacts with chlorine gas to produce a compound XCl₃. XCl₃ is electron deficient and easily reacts with NH₃ to form Cl₃X $$ \leftarrow $$ NH₃ adduct ; however, XCl₃ does not dimerize X is :