Map pling A student was given a solid containing a mixture of nitrate salts. The

Question

Map pling A student was given a solid containing a mixture of nitrate salts. The sample completely dissolved in water and upon addition of dilute HCI, no precipitate formed. The pH was lowered to about 1 and H2S was bubbled through the solution. No precipitate formed. The pH was adjusted to 8 and H2S was again bubbled in. This time, a precipitate formed. Which compounds might have been present in the unknown? Cr(NO33 Zn (NO32 Fe(NO3)3 Ca (NO3) Pb(NO3)2 NaNO3 Cd(NO3)2 Sn(NO3)4. G Previous Give Up & View solution Check Answer Next Ext H Hint

Explanation / Answer

answer : Zn (NO3)2

explanation :

sample + dil HCl ----------------> No precipitate

that means first group cations are absent (1st group cations Ag+ , Pb+2 , Hg2+2)

sample + dil HCl + H2S ---------------> No precipitate

this means second group cations are absent

Pb+2 , Sn+2 , Bi+3 , ect

there is no test given for 3rd group so

Fe+3 , Cr+3 , Al+3 are absent

now :

test for 4th group. our objective

sample + H2S + basic medium -----------------> precipitate

may be 4th group cations Zn+2 , Co+2 , Ni+2 , Mn+2

among these four Zn+2 is given in our options .

so answer is Zn(NO3)2

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