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Byju's Answer

Standard XII

Chemistry

Colour

Group III cat...

Question

Group III cations are precipitated as ________.

Chlorides

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Hydroxides

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Sulphides

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Nitrates

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Solution

The correct option is B Hydroxides
The original solution from Group II is heated with conc. $H N O_{3}$ and adding solid $N H_{4} C l + N H_{4} O H$ solution in excess, the group III radicals gets precipitate as hydroxides $(A l^{3 +}, C r^{3 +}, F e^{3 +})$ .
Hence, option (c) is correct.

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Similar questions

Q. Group I cations are precipitated as ________.

Q. In group III, the basic radicals are precipitated as their _____.

Q. A solution containing a group-IV cation gives a precipitate on passing

H_{2} S

. A solution of this precipitate in

d i l . H C l

produces a white precipitate with basic

N a O H

solution and bluish-white precipitate with basic potassium ferrocyanide. The cation is:

Q. A solution contains a group IV cation. It's sulphide precipitate dissolves in

d i l . H C l

on boiling. On addition of

N a O H

to the dissolved sulphide precipitate solution in excess, a white precipitate is formed which turns brown due to atmospheric oxidation.
The cation is:

In qualitative analysis,

{I I I}^{r d}

group includes

F e^{3 +}, A l^{3 +}

and

C r^{3 +}

. The group reagent is ammonium hydroxide in the presence of ammonium chloride.

N H_{4} C I

is added to suppress the ionisation of

N H_{4} O H

so that only the

I I I^{r d}

group radicals are precipitated as their insoluble hydroxide and not the

I V^{t h}

and

V^{t h}

group radicals as the solubility products of their hydroxides are much higher. Before adding group reagent to the filtrate of IInd group, one drop of concentrated

H N O_{3}

(oxidising agent) is added and the content is boiled for 2-3 minutes and then cool because the solubility product of

F e (O H)_{2}

is very high as compared to

F e (O H)_{3}

. When a light bluish-green crystalline double salt-containing cations of III

^{r d}

group and zero groups are analysed. it responds to the following tests/reactions.
(a) Its aqueous solution gives a reddish-brown precipitate with an alkaline solution of potassium tetraiodomercurate (II)
(b) Its aqueous solution after boiling with conc.

H N O_{3}

gives a reddish-brown precipitate with sodium hydroxide.
(c) The solution of reddish-brown precipitate in oil.HCI gives blood red colouration with ammonium sulphocyanide and Prussian blue with potassium ferrocyanide.
(d) It's a very dilute solution gives a white precipitate with

(C H_{3} C O O)_{2} P b

solution and a white precipitate are only soluble in hot ammonium acetate.

Why one mL conc.

H N O_{3}

is added to

I I^{n d}

group filtrate before proceeding for

I I I^{r d}

group radicals?

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Group III cations are precipitated as ________.

The correct option is B HydroxidesThe original solution from Group II is heated with conc. HNO3 and adding solid NH4Cl+NH4OH solution in excess, the group III radicals gets precipitate as hydroxides (Al3+, Cr3+, Fe3+). Hence, option (c) is correct.

The correct option is B Hydroxides
The original solution from Group II is heated with conc. $H N O_{3}$ and adding solid $N H_{4} C l + N H_{4} O H$ solution in excess, the group III radicals gets precipitate as hydroxides $(A l^{3 +}, C r^{3 +}, F e^{3 +})$ .
Hence, option (c) is correct.