Chemistry Sample Questions

1. Your are given a white material which could be any of the following :
ZnO, ZnCO3, Zn(OH)2, ZnS, Zn(NH3)4Cl2.
What tests would you perform to identify the compd? Be specific. Tell what reagents you could use and what observations you could make.

2. A white amorphous powder A on heating yields a non-combustible gas B and a solid C. The latter compd assumes a yellow color on heating and changes to white on cooling. C dissolves in dil acids and the resultant soln gives a white ppt on adding K[Fe(CN)4] soln. A dissolves in dil HCl with the evolution of a gas which is identical in all respects with B. The gas B turns lime water milky which disappears on continuous passage of it. The soln of A as obtained above gives a white ppt D on addn of excess of NH4OH and passing H2S. Anther portion of the soln gives initially a white ppt E on addn of NaOH soln which dissolves on further addn of base. Identify A-E.