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A white amorp...

Question

A white amorphous powder (A) when heated gives a colourless gas (B), which turns lime water milky and the residue (C) which is yellow when hot but white when cold. The residue (C) dissolves in dilute HCl and the resulting solution gives a white precipitate on addition of potassium ferrocyanide solution. (A) dissolves in dilute HCl with the evolution of a gas which is identical in all respects with (B). The solution of (A) as obtained above gives a white precipitate (D) on addition of excess of $N H_{4} O H$ and on passing $H_{2} S$ . Another portion of this solution gives initially a white precipitate (E) on addition of NaOH which dissolves in excess of it. Compounds (A) to (D) are identified as:
(A) : $Z n C O_{3}$ , (B) : $C O_{2}$ , (C) : $Z n O$ , (D) : $Z n S$ and (E) : $Z n (O H)_{2}$
If true enter 1, else enter 0.

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Solution

Zinc carbonate (A) is the white amorphous solid which on heating gives colourless gas (B) which is carbon dioxide and the residue (C) which is zinc oxide.
$Z n C O_{3} Δ - \to C O_{2} B + Z n O C$
Carbon dioxide gas turns lime water milky and zinc oxide is yellow when hot and white when cold.
Zinc oxide dissolves in dilute HCl to form zinc chloride which reacts with potassium ferrocyanide to form white ppt.
Zinc carbonate dissolves in dil HCl to liberate carbon dioxide gas (B).
$Z n C O_{3} + 2 H C l \to Z n C l_{2} + H_{2} O + C O_{2} ↑$
Ammonium hydroxide neutralizes excess HCl.
Zn(II) ions react with hydrogen sulphide to give a white ppt D which is ZnS.
$Z n^{2 +} + S^{2 -} \to Z n S ↑$
Zn(II) ions react with NaOH to form white precipitate E which is zinc hydroxide.
$Z n^{2 +} + 2 N a O H \to Z n (O H)_{2} w h i t e p p t, E$
This ppt dissolves in excess NaOH
$Z n (O H)_{2} w h i t e p p t, E + 2 N a O H \to N a_{2} Z n O_{2} s o d i u m z i n c a t e + 2 H_{2} O$

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Q. A white amorphous powder

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B

and a solid

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C

dissolves in dilute hydrochloric acid and the resulting solution gives a white precipitate with

K_{4} F e (C N)_{6}

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Q. Read the following statements:
(i) A white amorphous powder (A) on strongly heating gives a colourless non-combustile gas (B) and solid (C).
(ii) The gas (B) turns lime water milky and turbidity disappear with the passage of excess of gas.
(iii) The solution (C) in dilute HCl gives a white precipitate with an aqueous solution of

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If true enter 1, else enter 0.

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If true enter 1, else enter 0.

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