Explain the following
(a) Although Au is soluble in aqua-regia, Ag is not
(b) Zinc and hot copper is used for recovery of Ag from the complex `[Ag(CN)_(2)]^(-)`
(c) Aluminium metal is frequently used as a reducing agent for extraction of metal such as chromium manganese etc.
(d) Partial roasting of sulphide ore is done in the metallurgy of copper.

STATEMENT-1 : Zinc and not copper is used in the recovery of silver from the complex [Ag(CN)_(2)]^(-) and STATEMENT-2 : Zinc is more powerful oxidising agent than copper.

STATEMENT-1 : Zinc and not copper is used in the recovery of silver from the complex [Ag(CN)_(2)]^(-) and STATEMENT-2 : Zinc is more powerful oxidising agent than copper.

(a) Indicate the temperature at which carbon can be used as reducing agent for FeO . (b) Define flux. ( c) Metal usually do not occur in nature as nitrates. Why ? (d) Metal such as Cu, Ag, Zn etc. occur in nature as sulphide rather than oxides. Why ?

Explain the following (a) CO_(2) is a better reducing agent below 710 K whereas CO is a better reducing agent above 710 K . (b) Generally sulphide ores are converted into oxides before reduction. ( c) Silica is added to the sulphide ore of copper in the reverberatory furnance. (d) Carbon and hydrogen are not used as reducing agents at high temperature. (e) Vapour phase refining method is used for the purification of Ti

Explain the following : (a) Why is tungsten used almost exclusively for filament of incandescent lamp ? (b) Why are the conductors of electric heating devices, such as toaster and electric irons, made of an alloy rather than a pure metal ? ( c) Why is the series arrangement not used for domestic circuits ? (d) How does the resistance of a wire vary with its cross-sectional area ? (e ) Why are copper and aluminium wires usually employed for electricity transmission.

Metallic gold is frequently found in aluminosllicate rocks and it is finely dispersed among other minerals.It may be extracted by treating the crushed rock with aerated potassium cyanide solution.During this process metallic gold is slowly converted to [Au(CN)_2]^(-) , which is soluble in water.After equilibrium has been reached.the aqueous phase is pumped off and the metallic gold is recovered from it by reacting the gold complex with zinc, which is converted to [Zn(CN)_4]^(2-) . Gold in nature is frequently alloyed with silver which is also oxidised by aerated sodium cyanide solution.Silver occurs as native as well as sulphurised ore. Which of the following statements is correct ?

During the purification of copper by electrolysis: (a)the anode used is made of copper ore (b)pure copper is deposited on the cathode (c)the impurities such as Ag, Au present in solution as ions (d)concentration of CuSO_4 solution remains constant during dissolution of Cu

Select from the given below (A to F), the one substance in each case which matches the descriptions given in parts (i) to (vi). Copy and complete the given grid with your answers as shown for part (i). (A) Ammonia (B) Copper oxide (C) Copper sulphate (D) Hydrogen chloride (E) Hydrogen sulphide (F) Lead bromide (i) Although this compound is not a metal hydroxide, its aqueous solution is alkaline in nature. (ii) A solution of this compound is used as the electrolyte when copper is purified. (iii) When this compound is electrolysed in the molten state, lead is obtained at the cathode. (iv) This compound can be oxidized to chlorine. (v) This compound smells of rotten eggs. (vi) This compound can be reduced to copper when heated with coke.

Coordination compounds plays many important roles in animals and plants. The are essential in the storage and transport of oxygen as electrons transfer agents as catalysts and in photosynthesis Wide range of application in daily life takes place through formation of complexes Photographic fixing qualitative and quantitative analysis purification of water metallurgical extraction are some specific worth mentioning Extraction of Ag from sulphide ore and removal of unreacted silver from photographic plate involve complexes: (a) [Ag(S_(2)O_(3))_(2)]^(3-) ion both (b) [Ag(CN)_(2)]^(Θ) in both (c) [Ag(S_(2)O_(3))]^(3-) , [Ag(CN)_(2)]^(Θ) (d) [Ag(CN)_(2)]^(Θ) ,[Ag_(2)(S_(2)O_(3))_(2)]^(3-) .

Metals are extracted from their ores by a wide variety of techniques. The most common ores are oxides. Most metals are obtained by direct treatment of theirs ores with chemical agents, but the extraction of certain others require electrolysis. An example of the former type of process is the extraction of iron from its oxide, described by the following equation : Fe_(2) O_(3) + 3C rarr 2Fe + 3CO The relative ease of extraction of a metal from its oxide can be estimated using the Ellingham diagram, as shown in the figure. The diagram plots the free energies of formation of various oxides per mole of consumed oxygen as a function of absolute temperature. Which of the following best explains why the free energy of formation of Fe_(2)O_(3) becomes less negative as the temperature is increased.