The aqueous solution of inorganic compound
(X) yielded a white precipitate when treated with dilute
HNO3 and
AgNO3. Another sample of the solution of
(X) when treated with
NaOH gave a white precipitate first which dissolved in excess of
NaOH yielding a colorless solution. When
H2S gas was passed through that solution a white precipitate was obtained.
Identify the compound (X) and give the reactions.