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PRACTICAL CHEMISTRY

37554 An aqueous solution of a salt $X$ turns blood red on treatment with $C N S^{-}$ and blue on treatment with $K_{4} [F e (C N)_{6}] .$ $X$ also gives a positive chromyl chloride test.The salt $X$ is

1

C u C l_{2}

2

F e C l_{3}

3

C u (N O_{3})_{2}

4

F e (N O_{3})_{3}

Explanation:

$F e^{3 +}$ radical gives blood red with $S C N^{-}$
$F e^{3 +} + 3 C N S^{-} \to F e {(C N S)}_{3}$ Ferric sulphocyanide (Blood red colouration)
$F e^{3 +}$ gives blue coloue on treatment with $K_{4} [F e {(C N)}_{6}]$
$4 F e^{3 +} + 3 K_{4} [F e {(C N)}_{6}] \to \underset{\begin{matrix} F e r r i c f e r r o c y a n i d e \\ (Pr u s s i a n b l u e) \end{matrix}}{12 K^{+} + F e_{4} {[F e {(C N)}_{6}]}_{3}}$
$C l^{-}$ radical gives chromyl chloride test.

PRACTICAL CHEMISTRY

37555 The cation that will not be precipitated by $H_{2} S$ in the presence of dil. $H C l$ is

1

P b^{2 +}

2

C u^{2 +}

3

C o^{2 +}

4

A s^{3 +}

Explanation:

$C o^{+ 2}$ ion is precipitated by $H_{2} S$ in presence of $N H_{4} O H$ which is a group reagent of group $I V$ in cationic analysis .

PRACTICAL CHEMISTRY

37556 Sodium Carbonate cannot be used in place of $(N H_{4})_{2} C O_{3}$ for the identification of $C a^{2 +}, B a^{2 +}$ and $S r^{2 +}$ ions (in group $V$ ) during mixture analysis because

1

M g^{2 +}

ions will also be precipitated

2 Concentration of

C O_{3}^{2 -}

ions is very low

3 Sodium ions will react with acid radicals

4

N a^{+}

ions will interfere with the detection of

C a^{2 +}

,

B a^{2 +}

,

S r^{2 +}

ions

Explanation:

If $N a_{2} C O_{3}$ is used in place of $(N H_{4})_{2} C O_{3}$ . It will precipitate group $V$ radicals as well as magnesium radicals. The reason for this is the high ionization of $N a_{2} C O_{3}$ in water into $N a^{+}$ and $C O_{3}^{-}$ . Now the higher concentration of $C O_{3}^{-}$ is available which exceeds the solubility product of group $V$ radicals as well as that of magnesium radicals

PRACTICAL CHEMISTRY

37557 The substance used as froth stabilisers in forth-floatation process is

1 Potassium ethyl xanthate

2 Aniline

3 Sodium cyanide

4 Copper sulphate

PRACTICAL CHEMISTRY

37554 An aqueous solution of a salt $X$ turns blood red on treatment with $C N S^{-}$ and blue on treatment with $K_{4} [F e (C N)_{6}] .$ $X$ also gives a positive chromyl chloride test.The salt $X$ is

1

C u C l_{2}

2

F e C l_{3}

3

C u (N O_{3})_{2}

4

F e (N O_{3})_{3}

Explanation:

$F e^{3 +}$ radical gives blood red with $S C N^{-}$
$F e^{3 +} + 3 C N S^{-} \to F e {(C N S)}_{3}$ Ferric sulphocyanide (Blood red colouration)
$F e^{3 +}$ gives blue coloue on treatment with $K_{4} [F e {(C N)}_{6}]$
$4 F e^{3 +} + 3 K_{4} [F e {(C N)}_{6}] \to \underset{\begin{matrix} F e r r i c f e r r o c y a n i d e \\ (Pr u s s i a n b l u e) \end{matrix}}{12 K^{+} + F e_{4} {[F e {(C N)}_{6}]}_{3}}$
$C l^{-}$ radical gives chromyl chloride test.

PRACTICAL CHEMISTRY

37555 The cation that will not be precipitated by $H_{2} S$ in the presence of dil. $H C l$ is

1

P b^{2 +}

2

C u^{2 +}

3

C o^{2 +}

4

A s^{3 +}

Explanation:

$C o^{+ 2}$ ion is precipitated by $H_{2} S$ in presence of $N H_{4} O H$ which is a group reagent of group $I V$ in cationic analysis .

PRACTICAL CHEMISTRY

37556 Sodium Carbonate cannot be used in place of $(N H_{4})_{2} C O_{3}$ for the identification of $C a^{2 +}, B a^{2 +}$ and $S r^{2 +}$ ions (in group $V$ ) during mixture analysis because

1

M g^{2 +}

ions will also be precipitated

2 Concentration of

C O_{3}^{2 -}

ions is very low

3 Sodium ions will react with acid radicals

4

N a^{+}

ions will interfere with the detection of

C a^{2 +}

,

B a^{2 +}

,

S r^{2 +}

ions

Explanation:

If $N a_{2} C O_{3}$ is used in place of $(N H_{4})_{2} C O_{3}$ . It will precipitate group $V$ radicals as well as magnesium radicals. The reason for this is the high ionization of $N a_{2} C O_{3}$ in water into $N a^{+}$ and $C O_{3}^{-}$ . Now the higher concentration of $C O_{3}^{-}$ is available which exceeds the solubility product of group $V$ radicals as well as that of magnesium radicals

PRACTICAL CHEMISTRY

37557 The substance used as froth stabilisers in forth-floatation process is

1 Potassium ethyl xanthate

2 Aniline

3 Sodium cyanide

4 Copper sulphate

PRACTICAL CHEMISTRY

37554 An aqueous solution of a salt $X$ turns blood red on treatment with $C N S^{-}$ and blue on treatment with $K_{4} [F e (C N)_{6}] .$ $X$ also gives a positive chromyl chloride test.The salt $X$ is

1

C u C l_{2}

2

F e C l_{3}

3

C u (N O_{3})_{2}

4

F e (N O_{3})_{3}

Explanation:

$F e^{3 +}$ radical gives blood red with $S C N^{-}$
$F e^{3 +} + 3 C N S^{-} \to F e {(C N S)}_{3}$ Ferric sulphocyanide (Blood red colouration)
$F e^{3 +}$ gives blue coloue on treatment with $K_{4} [F e {(C N)}_{6}]$
$4 F e^{3 +} + 3 K_{4} [F e {(C N)}_{6}] \to \underset{\begin{matrix} F e r r i c f e r r o c y a n i d e \\ (Pr u s s i a n b l u e) \end{matrix}}{12 K^{+} + F e_{4} {[F e {(C N)}_{6}]}_{3}}$
$C l^{-}$ radical gives chromyl chloride test.

PRACTICAL CHEMISTRY

37555 The cation that will not be precipitated by $H_{2} S$ in the presence of dil. $H C l$ is

1

P b^{2 +}

2

C u^{2 +}

3

C o^{2 +}

4

A s^{3 +}

Explanation:

$C o^{+ 2}$ ion is precipitated by $H_{2} S$ in presence of $N H_{4} O H$ which is a group reagent of group $I V$ in cationic analysis .

PRACTICAL CHEMISTRY

37556 Sodium Carbonate cannot be used in place of $(N H_{4})_{2} C O_{3}$ for the identification of $C a^{2 +}, B a^{2 +}$ and $S r^{2 +}$ ions (in group $V$ ) during mixture analysis because

1

M g^{2 +}

ions will also be precipitated

2 Concentration of

C O_{3}^{2 -}

ions is very low

3 Sodium ions will react with acid radicals

4

N a^{+}

ions will interfere with the detection of

C a^{2 +}

,

B a^{2 +}

,

S r^{2 +}

ions

Explanation:

If $N a_{2} C O_{3}$ is used in place of $(N H_{4})_{2} C O_{3}$ . It will precipitate group $V$ radicals as well as magnesium radicals. The reason for this is the high ionization of $N a_{2} C O_{3}$ in water into $N a^{+}$ and $C O_{3}^{-}$ . Now the higher concentration of $C O_{3}^{-}$ is available which exceeds the solubility product of group $V$ radicals as well as that of magnesium radicals

PRACTICAL CHEMISTRY

37557 The substance used as froth stabilisers in forth-floatation process is

1 Potassium ethyl xanthate

2 Aniline

3 Sodium cyanide

4 Copper sulphate

PRACTICAL CHEMISTRY

37554 An aqueous solution of a salt $X$ turns blood red on treatment with $C N S^{-}$ and blue on treatment with $K_{4} [F e (C N)_{6}] .$ $X$ also gives a positive chromyl chloride test.The salt $X$ is

1

C u C l_{2}

2

F e C l_{3}

3

C u (N O_{3})_{2}

4

F e (N O_{3})_{3}

Explanation:

$F e^{3 +}$ radical gives blood red with $S C N^{-}$
$F e^{3 +} + 3 C N S^{-} \to F e {(C N S)}_{3}$ Ferric sulphocyanide (Blood red colouration)
$F e^{3 +}$ gives blue coloue on treatment with $K_{4} [F e {(C N)}_{6}]$
$4 F e^{3 +} + 3 K_{4} [F e {(C N)}_{6}] \to \underset{\begin{matrix} F e r r i c f e r r o c y a n i d e \\ (Pr u s s i a n b l u e) \end{matrix}}{12 K^{+} + F e_{4} {[F e {(C N)}_{6}]}_{3}}$
$C l^{-}$ radical gives chromyl chloride test.

PRACTICAL CHEMISTRY

37555 The cation that will not be precipitated by $H_{2} S$ in the presence of dil. $H C l$ is

1

P b^{2 +}

2

C u^{2 +}

3

C o^{2 +}

4

A s^{3 +}

Explanation:

$C o^{+ 2}$ ion is precipitated by $H_{2} S$ in presence of $N H_{4} O H$ which is a group reagent of group $I V$ in cationic analysis .

PRACTICAL CHEMISTRY

37556 Sodium Carbonate cannot be used in place of $(N H_{4})_{2} C O_{3}$ for the identification of $C a^{2 +}, B a^{2 +}$ and $S r^{2 +}$ ions (in group $V$ ) during mixture analysis because

1

M g^{2 +}

ions will also be precipitated

2 Concentration of

C O_{3}^{2 -}

ions is very low

3 Sodium ions will react with acid radicals

4

N a^{+}

ions will interfere with the detection of

C a^{2 +}

,

B a^{2 +}

,

S r^{2 +}

ions

Explanation:

If $N a_{2} C O_{3}$ is used in place of $(N H_{4})_{2} C O_{3}$ . It will precipitate group $V$ radicals as well as magnesium radicals. The reason for this is the high ionization of $N a_{2} C O_{3}$ in water into $N a^{+}$ and $C O_{3}^{-}$ . Now the higher concentration of $C O_{3}^{-}$ is available which exceeds the solubility product of group $V$ radicals as well as that of magnesium radicals

PRACTICAL CHEMISTRY

37557 The substance used as froth stabilisers in forth-floatation process is

1 Potassium ethyl xanthate

2 Aniline

3 Sodium cyanide

4 Copper sulphate

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