Which one of the following ores is best concentrated by froth flotation method?
Siderite
Galena
Malachite
Malachite
In the context of the Hall-Heroult process for the extraction of Al, which of the following statements is false?
CO and CO2 are produced in this process
Al2O3 is mixed with CaF2 which lowers the melting point of the mixture and brings conductivity
Al3+ is reduced at the cathode to form Al
Al3+ is reduced at the cathode to form Al
The metal that cannot be obtained by electrolysis of an aqueous solution of its salts is
Ag
Ca
Cu
Cu
Which series of reactions correctly represents chemical relations related to iron and its compound?
Which method of purification is represented by the following equation
zone refining
cupellation
Polling
Polling
D.
Polling
Van-Arkel (and de-Boiser) process is based on the thermal decomposition of a volatile compound like an iodide, which is first formed by direct combination of metal to be purified and iodine.
The metallic iodide is then decomposed when heated at a higher temperature and thus the metal obtained in the purest form. Titanium and zirconium are purified by this method.
Which of the following factors is of no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?
Metal sulphides are thermodynamically more stable than CS2
CO2 is thermodynamically more stable than CS2
Metal sulphides are less stable than the corresponding oxides
Metal sulphides are less stable than the corresponding oxides
During the process of electrolytic refining of copper, some metals present as impurity settle as ‘anode mud’ These are
Sn and Ag
Pb and Zn
Ag and Au
Ag and Au
Which one of the following ores is best concentrated by froth – floatation method?
Magnetite
Malachite
Galena
Galena