5 questions from 2021
The reaction of \( \mathrm{K_3[Fe(CN)_6]} \) with freshly prepared \( \mathrm{FeSO_4} \) solution produces a dark blue precipitate called Turnbull’s blue. Reaction of \( \mathrm{K_4[Fe(CN)_6]} \) with the \( \mathrm{FeSO_4} \) solution in complete absence of air produces a white precipitate X, which turns blue in air. Mixing the \( \mathrm{FeSO_4} \) solution with \( \mathrm{NaNO_3} \), followed by a slow addition of concentrated \( \mathrm{H_2SO_4} \) through the side of the test tube produces a brown ring.
Among the following, the brown ring is due to the formation of:
A mixture of two salts is used to prepare a solution \( S \), which gives the following results:
$ \text{White precipitate(s) only} \xleftarrow[\text{Room temperature}]{\text{Dilute NaOH (aq.)}} \begin{matrix} \text{S} \\ \text{(aq. solution} \\ \text{of the salts)} \end{matrix} \xrightarrow[\text{Room temperature}]{\text{Dilute HCl (aq.)}} \text{White precipitate(s) only} $
The correct option(s) for the salt mixture is(are):
The reaction of \( \mathrm{K_3[Fe(CN)_6]} \) with freshly prepared \( \mathrm{FeSO_4} \) solution produces a dark blue precipitate called Turnbull’s blue. Reaction of \( \mathrm{K_4[Fe(CN)_6]} \) with the \( \mathrm{FeSO_4} \) solution in complete absence of air produces a white precipitate X, which turns blue in air. Mixing the \( \mathrm{FeSO_4} \) solution with \( \mathrm{NaNO_3} \), followed by a slow addition of concentrated \( \mathrm{H_2SO_4} \) through the side of the test tube produces a brown ring.
Precipitate X is:
Reaction of \( x \) \( \text{g} \) of \( \text{Sn} \) with \( \text{HCl} \) quantitatively produced a salt. Entire amount of the salt reacted with \( y \) \( \text{g} \) of nitrobenzene in the presence of required amount of \( \text{HCl} \) to produce \( 1.29 \, \text{g} \) of an organic salt (quantitatively).
(Use Molar masses (in \( \text{g mol}^{-1} \)) of H, C, N, O, Cl and Sn as \( 1 \), \( 12 \), \( 14 \), \( 16 \), \( 35 \) and \( 119 \), respectively)
The value of \( y \) is ____________.
Reaction of \( x \) \( \text{g} \) of \( \text{Sn} \) with \( \text{HCl} \) quantitatively produced a salt. Entire amount of the salt reacted with \( y \) \( \text{g} \) of nitrobenzene in the presence of required amount of \( \text{HCl} \) to produce \( 1.29 \, \text{g} \) of an organic salt (quantitatively).
(Use Molar masses (in \( \text{g mol}^{-1} \)) of H, C, N, O, Cl and Sn as \( 1 \), \( 12 \), \( 14 \), \( 16 \), \( 35 \) and \( 119 \), respectively)
The value of \( x \) is ____________.
