1. Tardigrade
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  3. Chemistry
  4. When H2S gas is passed through a hot acidic aqueous solution containing Al3+, Cu2+, Pb 2+ and Ni2+, a precipitate is formed, which consists of

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Q. When $H_{2}S$ gas is passed through a hot acidic aqueous solution containing $Al^{3+}, Cu^{2+}, Pb^ {2+} and Ni^{2+}, a$ precipitate is formed, which consists of

KVPYKVPY 2015

Solution:

When $H_{2}S$ gas is passed through a hot acidic aqueous solution containing AI$^{3+},\,Cu^{2-},\, Pb^{2+}$ and $Ni^{2+},$ precipitate of only group $II$ cations is formed. Among the given cations, $Pb^{2+}$ and $Cu^{2+}$ lie in group $2$ cations.
$Cu ^{2+}+ H _{2} S \longrightarrow \underset{(\text { Black ppt. })}{ CuS }+2 H ^{+}$
$Pb ^{2+}+ H _{2} S \longrightarrow \underset{(\text { Black ppt. })}{ PbS }+2 H ^{+}$