JEE Advanced 2021 · Paper 1 · Chemistry Q16

ChemistryMultiple correct+4 / -2Question 35 of 57

A mixture of two salts is used to prepare a solution $\mathbf S$ , which gives the following results:

$\mathbf S$ (aq solution of the salts) + dilute NaOH(aq), room temperature → white precipitate(s) only
$\mathbf S$ + dilute HCl(aq), room temperature → white precipitate(s) only

The correct option(s) for the salt mixture is(are)

\ce{Pb(NO3)2}

and

\ce{Zn(NO3)2}

\ce{Pb(NO3)2}

and

\ce{Bi(NO3)3}

\ce{AgNO3}

and

\ce{Bi(NO3)3}

\ce{Pb(NO3)2}

and

\ce{Hg(NO3)2}

Answer and worked solution

Official answer: A, B

Requirement. The mixture must give only white precipitates with both dilute NaOH and dilute HCl.

Check each option.

(A) NaOH gives white $\ce{Pb(OH)2}$ and $\ce{Zn(OH)2}$ . HCl gives white $\ce{PbCl2}$ . True.
(B) NaOH gives white $\ce{Pb(OH)2}$ and $\ce{Bi(OH)3}$ . HCl gives white $\ce{PbCl2}$ (and white BiOCl on hydrolysis). True.
(C) NaOH gives brown $\ce{Ag2O}$ . False.
(D) NaOH gives yellow HgO. False.

(A), (B)

Topics:Cation analysis

JEE Advanced 2021 · Paper 1, Chemistry question 16