IIT Chemistry Sample Paper 1
- An aq soln of a gas X gives the fol reactions:
Identify X and give all reactions taking place.
- It decolorizes an acidified soln of K2Cr2O7
- On boiling it with H2O2, cooling it and then adding an aq soln of BaCl2 a ppt insoluble in dil HCl is obtained.
- On passing H2S a white turbidity is obtained.
- The gas liberated on heating a mix of 2 salts with NaOH gives a reddish brown ppt with an alk soln K2HgI4. The soln (aq) of the mix on treatment with BaCl2 gives a white pt which is sparingly solution in conc HCl. On heating the mix with K2Cr2O7 and conc H2SO4 red vap of A are produced. The aq soln of the mix gives a deep blue coloration B with pot ferricyanide soln. Identify the radicals and write balanced eqns for formation of A and B?
- A black colored compd A on reaction with dil H2SO4 gives a gas B which on passing in a soln of an acid C gives a white turbidity D. Gas B when passed thro acidified soln of E gives a ppt F solution in dil HNO3. After boiling this soln when an excess of ammonium hydroxide is added a blue colored compd G is formed. To this soln on addn of acetic acid and aq pot ferrocyanide a chocolate ppt H is obtained. On addn of an aq soln of E a white ppt insol in HNO3 is obtained. Identify A to H.
- A mix of 2 salts were treated as follows:
Identify the 2 salts. Give ionic reactions for the tests (i) to (iii).
- The mix was heated with manganese dioxide and conc H2SO4 when yellowish green gas was obtained.
- The mix on heating with sod hydroxide soln gave a gas, which turned red litmus blue.
- Its soln in water gave blue ppt with pot ferricyanide and red coloration with amm thiocyanate.
- The mix was boiled with pot hydroxide and the liberated gas was bubbled thro an alk soln of K2HgI4 to give brown pt.
- A certain inorganic compd A on heating loses its water of crystallization. On further heating a blackish powder B and 2 oxides of S - C and D are obtained, the powder B on boiling with HCl gives a yellow soln E. When H2S is passed thro E a white turbidity F and apple green soln G are obtained. The soln E on treatment with thiocyanate ions gives a blood red color compd H. Identify A to H.
- A green colored metallic chloride A when treated with sod hydroxide and H2O2 gives a yellow soln due to the formation of compd B. The color of this soln changes to orange when dil H2SO4 is added to it. It is due to the formation of compd C. When KCl is heated along with C in presence of conc H2SO4 a red volatile liq D is formed. The compd C when treated with amm chloride forms compd E which decomposes on heating giving a colorless gas F water and green residue G. When Mg is burnt in the presence of F a white solid H is formed. The latter on hydrolysis forms a gas I which gives white fumes with HCl. Identify A to I giving involved eqns.
- 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.
- 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.
- A colorless solid A on heating gives a white solid B and a gas C; B gives off reddish brown fumes on treatment with dil acids. On heating with NH4Cl, B gives a colorless gas D and a residue E. The compd A also gives colorless gas F on heating with ammonium sulphate and white residue G. Both E and G impart yellow color to the Bunsen flame. C forms white powder with strongly heated Mg metal. The white powder forms Mg(OH)2 with H2O. The gas D on the other hand is observed by heated Ca which gives off ammonia on hydrolysis. Identify the substance A to G and give reactions for the changes involved.
- A mix of 3 gases A, B, C is passed first into acidified dichromate solution when A is absorbed turning the soln green. The remainder of the gas is passed through excess of lime water which turns milky resulting in the absorption of B. The residual gas C is absorbed by alk pyrogallol soln. However the original mix does not turn lead acetate paper black. Identify A, B, C.