Chemistry Practical

The aqueous solution of inorganic compound $$(X)$$ yielded a white precipitate when treated with dilute $$HNO_3$$ and $$AgNO_3$$. 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 $$H_2S$$ gas was passed through that solution a white precipitate was obtained. 
Identify the compound $$(X)$$ and give the reactions.
Identify the inorganic salt $$A$$ whose aqueous solution gives following reactions.
(i) pale yellow precipitate with $$AgNO_3$$ solution, insoluble in dil $$HNO_3$$
(ii) white precipitate with $$NH_4OH$$ and also with $$NaOH$$ solution. However the precipitate does not dissolve in excess of $$NH_4OH$$ but soluble in excess of $$NaOH$$.
Identify $$(A),\:(B),\:(C)$$ & $$(D)$$ and give their chemical formulae:
(i) $$(A)+NaOH\overset{Heat}{\longrightarrow} NaCl+NH_3+H_2O$$
(ii) $$NH_3+CO_2+H_2O\longrightarrow (B)$$
(iii) $$(B)+NaCl\longrightarrow (C)+NH_4Cl$$
(iv) $$(C)\overset{Heat}{\longrightarrow} Na_2CO_3+H_2O+(D)$$
An inorganic lewis acid $$[X]$$ gives gelatinous white ppt. with $$NH_4OH$$ in presence of $$NH_4Cl$$. $$[X]$$ will respond to which of the following characteristics :
A test tube containing a nitrate and another containing a bromide and $$MnO_2$$ are treated with conc. $$H_2SO_4$$. The brown fumes evolved are passed in water. The water will be coloured by the :