General Principles And Processes of Isolation Of Elements

Which of the following is not an ore of iron ?

• Limonite

• Caniterite

• Magnetite

• None of these

Thermite is a mixture of iron oxide and :

• zinc powder

• potassium metal

• sodium shavings

• aluminium powder

In the extraction of copper from sulphide ore the metal is formed by reduction of Cu₂O with

• FeS

• CO

• Cu₂S

• SO₂

Extraction of gold (Au) involves the formation of complex ions X and Y.

Gold ore $\underset{{\mathrm{CN}}^{-}, {\mathrm{H}}_2\mathrm{O}, {\mathrm{O}}_2}{\overset{\mathrm{Roasting}}{\to }}$ HO^- + X $\stackrel{\mathrm{Zn}}{\to }$ Y + Au

X and Y respectively are

• AuCN${}_2^{-}$ and Zn(CN)${}_4^{2-}$

• Au(CN)${}_4^{3-}$ and  Zn(CN)${}_{\mathrm{}}^{$ {}_4^{2-}$}$

• Au(CN)${}_3^{-}$ and Zn(CN)${}_6^{4-}$

• Au(CN)${}_4^{-}$ and Zn(CN)${}_3^{-}$

The composition of carnalite is

• $\mathrm{KCl}·{\mathrm{MgCl}}_2·6{\mathrm{H}}_2\mathrm{O}$

• Na₂Al₂O₃

• Fe₃O₄

• Na₃AlF₆

Roasted copper pyrite on smelting with sand produces

• FeSiO₃ as fusible slag and Cu₂S as matte

• CaSiO₃ as infusible slag and Cu₂O as matte

• Ca₃(PO₄)₂ as fusible slag and Cu₂S as matte

• Ca₃(PO₄)₂ as infusible slag and Cu₂S as matte

Which of the following metals has the largest abundance in the earth's crust? 

• Aluminium

• Calcium

• Magnesium

• Sodium

Prepare CuSO₄.5H₂O starting from copper pyrites.

In aluminium extraction by the Bayer process, alumina is extracted from bauxite by sodium hydroxide at high temperatures and pressures

${\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right) + 2{\mathrm{OH}}^{-}\left(\mathrm{aq}\right) \to 2{\mathrm{Al}}_2{\mathrm{O}}_2^{-}\left(\mathrm{aq}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Solid impurities such as Fe₂O₃ and SiO₂ are removed and then Al(OH)₄^- is reprecipitated

$2\mathrm{Al}(\mathrm{OH}{)}_4^{-} \to {\mathrm{Al}}_2{\mathrm{O}}_3·3{\mathrm{H}}_2\mathrm{O}(\mathrm{s}) +2{\mathrm{OH}}^{-}(\mathrm{aq}).$In the industrial world

• carbon dioxide is added to precipitate the alumina

• temperature and pressure are dropped and the super saturated solution seeded

• both (A) and (B) are practised

• the water is evaporated

Which is the chief ore of copper?

• Galena

• Copper pyrites

• Sphalerite

• Siderite