When an inorganic compound (X) having 3e-2e as well as 2e-2e bonds reacts with ammonia gas at a certain temperature, gives a compound (Y) iso-structural with benzene. Compound (X) with ammonia at a high temperature, produces a hard substance (Z). Then
(A) (X) is B2H6
(B) (Z) is known as inorganic graphite
(C) (Z) having structure similar to graphite
(D) (Z) having structure similar to (X)