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Grade 11Inorganic Chemistry

A white amorphous powder (A) on heating yields a colourless, non-combustible gas (B) and a solid (C). The latter compound assumes a yellow colour on heating and changes to white on cooling. ‘C’ dissolves in dilute acid and the resulting solution gives a white precipitate on adding K4Fe(CN)6 solution.
‘A’ dissolves in dilute HCI with the evolution of gas which is identical in all respects with ‘B’. The gas ‘B’ turns lime water milky, but the milkinness disappears with the continuous passage of gas. The solution of ‘A’, as obtained above, gives a white precipitate (D) on the addition of excess of NH4OH and passing H2S. Another portion of the solution gives initially a white precipitate (E) on the addition of sodium hydroxide solution, which dissolves on further adition of the base. Identify the compounds A, B, D, and E.

Profile image of Simran Bhatia
12 Years agoGrade 11
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1 Answer

Profile image of Aditi Chauhan
12 Years ago
(i) ZnCO3 \overset{\Delta }{\rightarrow}ZnO + CO2
(A) (C) (B)
(ii) ZnO + 2HCI → H2O + ZnCI2­
(C) (soluble)
(iii) 2ZnCI2 + K­4 [Fe(CN)6] → 4KCI + Zn2 p[Fe (CN)6]↓
(white ppt)
(iv) ZnCO3 + HCI → CO2 + ZnCI2­
(A) (soluble)
(v) CO2 + Ca(OH)2 → CaCO3 + H2O
(Milky)
(vi) CaCO3 + CO22O → Ca(HCO3)2
(vii) ZnCI2 + H2S \overset{NH_{4}OH }{\rightarrow}2HCI + ZnS ↓
(white)
(viii) ZnCI2 + 2NaOH → Zn(OH)2
(white) E
(ix) Zn(OH)2 + 2NaOH → Na2ZnO2 + H2
sod. Zincate
(soluble)