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Which of the following is a pure substance made of only one type of atom
Sand and iron filings
Air
Salt water
Oxygen (O₂)
Which of the following is a compound
Sodium chloride (NaCl)
Oxygen (O₂)
Sand and iron filings
Gold (Au)
Which of the following is a mixture
Water (H₂O)
Sodium chloride (NaCl)
Gold (Au)
Air
The process of crushing ores into small particles using machines is called
Refining
Grinding
Roasting
Calcination
The unwanted impurities in ores such as mud sand and rocks are called
Slag
Mineral
Gangue
Alloy
The process of removing impurities from ores to increase the percentage of metal is called
Refining
Concentration
Reduction
Calcination
Which method is used if the ore and impurities differ in density
Roasting
Magnetic separation
Hydraulic washing
Froth floatation
If one substance is magnetic and the other is not which separation method is used
Distillation
Calcination
Magnetic separation
Froth floatation
Froth floatation is used when
One substance is hydrophilic and the other hydrophobic
Both substances are magnetic
The ore is soluble in water
Both substances have the same density
Roasting converts sulphide ores into
Alloys
Carbonates
Metals
Oxides
Calcination converts carbonate ores into
Sulphides
Slags
Oxides
Alloys
Which of the following is converted into ZnO by roasting
ZnS
NaCl
Fe₂O₃
CaCO₃
The process of heating ores with reducing agents beyond their melting points is called
Refining
Smelting
Roasting
Calcination
The by-product formed when impurities combine during smelting is called
Slag
Electrode
Gangue
Alloy
Refining is done to
Crush ores into powder
Convert ores into oxides
Extract ores from the earth
Remove remaining impurities from metals
Which refining method is used for metals with a low boiling point like mercury
Electro-refining
Smelting
Calcination
Distillation
