Properties of elements X:
(i) Its amide is used as a reducing agent
(ii) Its amalgam is used as reducing agent
Properties of element Y:
(i) It is an octaatomic molecule
(ii) It is diamagnetic in ground state but paramagnetic in vapour phase
Properties of element Z:
(i) Its diatomic molecule is paramagnetic
(ii) Its allotrope is an absorber of UV radiation
(iii) IT supports combustion
Compound of X,Y and Z on reaction with Y form a compound A. Out of the following which statement is not correct about compound A?

Options

A. used in iodometry
B. used in development of photographich plates
C. one reaction with `FeCl_(3)` it gives violet colour, which disappear after some time
D. The oxidation number of Y in this compound is `+4`

Answer

D