Light green (Compound 'A')Δ−→ White Residue (B) High−−−→temp.C+D+E
(i) 'D' and 'E' are two acidic gas.
(ii) 'D' is passed through HgCl2 solution to give yellow ppt.
(iii) 'E' is passed through water first and then H2S is passed, white turbidity is obtained.
(iv) A is water-soluble and addition of HgCl2 in it, white ppt is obtained but white ppt does not turn into grey on addition of excess solution of 'A'.
Yellow ppt in the above observation is: