Question

Solution 'A' gives black ppt. With dil. HCl and H2S gas, which basic radical is present in given solution.

Answer 1

Answer:

Hg

2+

,Cu

2+

and Pb

2+

are the basic radicals formed when they are reacted with dil. HCl and H_2SH

2

S gas to form black precipitate.

Explanation: Dilute HCl and H_2SH

2

S gas are the reagents used for the qualitative analysis of Group II-A cations.

Group II-A cations are mercury (Hg^{2+})(Hg

2+

) , lead (Pb^{2+})(Pb

2+

) , Bismuth (Bi^{3+})(Bi

3+

) , Cadmium (Cd^{2+})(Cd

2+

) and copper (Cu^{2+})(Cu

2+

) .

These cations when reacted with the reagent forms respective salts.

Only mercury, lead and copper forms black precipitate with the reagent.

In a salt, the cationic part is considered as a basic radical and the anionic part is considered as the acidic radical.

So, from the salts of Group II-A, basic radicals would be Hg^{2+},Cu^{2+}\text{ and }Pb^{2+}Hg

2+

,Cu

2+

and Pb

2+

Answer 2

$Hg^{2+}, Cu^{2+}, and Pb^{2+}$ are the basic radicals present when they are reacted with dil.HCl and $H_2S$ gas forming Black ppt.

• The mentioned reagents Dil.HCl and $H_2S$ gas are used for the quantitative analysis of 'group-II A' cations.

• 'Group-II A' cations consist of five basic radicals, they are Mercury         ($Hg^{2+}$), Copper($Cu^{2+}$), Lead($Pb^{2+}$), Cadmium($Cd^{2+}$), and Bismuth($Bi^{3+}$).
• Out of the five basic radicals, only Mercury, Copper, and Lead forms black precipitate when reacted with the reagents.
• In a salt, the cationic part is called the basic radical and the anionic part is called the acid radical.