The chemical composition of slag formed during the smelting process in the extraction of copper is
FeSiO3
CuFeS2
Cu2S + FeO
Cu2O + FeS
Silver ornaments tum black in the atmosphere. It is due to the formation of
Ag2O, Ag2S
AgNO3, Ag2S
Ag(OH), Ag2CO3
Ag, Ag2O
A.
Ag2O, Ag2S
Silver is a highly unreactive metal so it does not react with the oxygen of air easily. But air usually contains a parts per billion concentrations of pollutant gases, such as HCl, H2S, SO2 , NO2 and ozone. The exposure of silver to H2S gas at 25°C and air containing 75% relative humidity produces a black coating consisting of silver sulphide (Ag2S) on its surface.
Similarly, the exposure of silver to NO2 gas at 25°C and air containing 75% relative humidity produces a thin film of AgNO3 (transparent) and Ag2O (black) on its surface. Thus, silver ornaments gradually turn black due to formation of layers of Ag2S and Ag2O.
The age of most ancient geological formation is estimated by
carbon dating
potassium-argon dating
radium-radon dating
uranium-lead dating
Malachite decomposed to give A+CO2+ H2O and compound A on reduction with carbon gives CO+B. Here, A and B are
CuO, Cu
Cu2O, CuO
Cu2O, Cu
CuCO3, Cu
Among the following statements, the incorrect one is
Calamine and siderite are carbonates
Argentite and cuprite are oxides
Zinc blende and pyrites are sulphides
Malachite and azurite are ores of copper
Calcination is used in metallurgy for removal of
water and sulphide
water and CO2
CO2 and H2S
H2O and H2S
In blast furnace, the highest temperature is in
reduction zone
slag zone
fusion zone
combustion zone
In the metallurgy of iron, when limestone is added to the blast furnace, the calcium ions are removed as
slag
gangue
metallic Ca
CaCO3
Of the following substances, the one which does not contain oxygen is
bauxite
dolomite
cryolite
epsomite
A smuggler could not carry gold by depositing iron on gold surface since
gold has higher standard reduction potential than iron
gold has lower standard reduction potential than iron
gold is denser
iron rusts