The correct option(s) to distinguish nitrate salts of {Mn}²+} and {Cu}²+} taken separately is (are) :- [JEE Adv 2018 P2]

{Mn}²+} shows the characteristic green colour in the flame test

Only {Cu}²+} shows the formation of precipitate by passing {H}₂{S} in acidic medium

Only {Mn}²+} shows the formation of precipitate by passing {H}₂{S} in faintly basic medium

{Cu}²+}{/}{Cu} has higher reduction potential than {Mn}²+}{/}{Mn} (measured under similar conditions)

Test Index

d and f block elements

Section: Chemistry

Question : 10 of 24

Marks: +1, -0

\mathrm{Mn}^{2+}

\mathrm{Cu}^{2+}

$\mathrm{Mn}^{2+}$ shows the characteristic green colour in the flame test
Only $\mathrm{Cu}^{2+}$ shows the formation of precipitate by passing $\mathrm{H}_2\mathrm{S}$ in acidic medium
Only $\mathrm{Mn}^{2+}$ shows the formation of precipitate by passing $\mathrm{H}_2\mathrm{S}$ in faintly basic medium
$\mathrm{Cu}^{2+}\text{/}\mathrm{Cu}$ has higher reduction potential than $\mathrm{Mn}^{2+}\text{/}\mathrm{Mn}$ (measured under similar conditions)

Solution:

\mathrm{Cu}^{+2}

and

\mathrm{Mn}^{+2}

both gives green colour in flame test and cannot distinguished.

\mathrm{Cu}^{+2}

belongs to group-II of cationic radical will gives ppt. of CuS in acidic medium.

\mathrm{Cu}^{+2}

and

\mathrm{Mn}^{+2}

both from ppt. in basic medium

\mathrm{Cu}^{+2}\text{/}\mathrm{Cu}=+0.34\,\mathrm{V}

(SRP

\mathrm{Mn}^{+2}\text{/}\mathrm{Mn}=-1.18\,\mathrm{V}

(SRP)

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