Basics of Extraction — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry Basics of Extraction MCQs with step-by-step solutions (12 questions). Part of Metals & Non-Metals. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Basics of Extraction · medium · theory
The naturally occurring compounds from which metals are extracted are called:
A. slag
B. salts only
C. alloys
D. ores ✓ Correct
Solution: Minerals from which a metal can be profitably extracted are called ores.
Q2 — Basics of Extraction · hard · theory
Highly reactive metals like sodium and aluminium are extracted from their molten compounds by:
A. filtration
B. electrolysis ✓ Correct
C. simple hand-picking
D. heating with carbon
Solution: Very reactive metals cannot be reduced by carbon, so they are obtained by electrolytic reduction.
Q3 — Basics of Extraction · hard · theory
Metals of medium reactivity, such as iron and zinc, are usually extracted from their oxides by:
A. sublimation
B. evaporation
C. electrolysis only
D. reduction with carbon ✓ Correct
Solution: Their oxides are reduced by heating with carbon (a cheaper reducing agent) to give the metal.
Q4 — Basics of Extraction · medium · theory
The chief ore of aluminium is:
A. bauxite ✓ Correct
B. rock salt
C. limestone
D. haematite
Solution: Aluminium is chiefly extracted from bauxite (aluminium oxide ore).
Q5 — Basics of Extraction · medium · theory
The chief ore of iron is:
A. galena
B. bauxite
C. cinnabar
D. haematite ✓ Correct
Solution: Haematite (Fe₂O₃) is a major iron ore.
Q6 — Basics of Extraction · hard · theory
Gold and silver are often found in nature in the free (native) state because they are:
A. very reactive
B. very unreactive (least reactive) ✓ Correct
C. non-metals
D. gases
Solution: Being at the bottom of the reactivity series, they do not readily combine with other elements and occur uncombined.
Q7 — Basics of Extraction · medium · theory
The branch of science dealing with the extraction of metals from their ores is called:
A. astronomy
B. biology
C. metallurgy ✓ Correct
D. geology
Solution: Metallurgy is the science and process of extracting and purifying metals.
Q8 — Basics of Extraction · easy · theory
A naturally occurring solid from which a metal can be extracted profitably and conveniently is called
A. an ore ✓ Correct
B. a slag
C. an alloy
D. a gangue
Solution: An ore is a mineral from which a metal can be extracted profitably. Not every mineral is an ore, only those rich enough to make extraction worthwhile.
Q9 — Basics of Extraction · easy · theory
The unwanted earthy or rocky impurities present along with the metal compound in an ore are known as
A. gangue ✓ Correct
B. ore
C. slag
D. flux
Solution: The undesirable impurities such as sand and rocky matter present in an ore are called gangue. These are removed during the concentration and extraction steps.
Q10 — Basics of Extraction · medium · theory
Highly reactive metals such as sodium, calcium and aluminium are extracted from their molten compounds by
A. reduction with carbon
B. heating the ore strongly in air
C. electrolysis of the molten compound ✓ Correct
D. simply washing the ore with water
Solution: Metals high in the reactivity series hold on to oxygen very strongly and cannot be reduced by carbon. They are obtained by electrolysis of their molten chlorides or oxides, in which electricity carries out the reduction.
Q11 — Basics of Extraction · hard · theory
Carbon is commonly used to reduce the oxides of moderately reactive metals such as zinc and iron, but it is NOT used to obtain aluminium from aluminium oxide. The reason is that
A. aluminium oxide does not contain any oxygen
B. carbon reacts violently with aluminium metal
C. aluminium is less reactive than carbon
D. aluminium is more reactive than carbon and holds its oxygen too strongly to be reduced by carbon ✓ Correct
Solution: A metal oxide can be reduced by carbon only if the metal is less reactive than carbon. Aluminium is more reactive than carbon, so carbon cannot pull oxygen away from aluminium oxide, and electrolysis is used instead.
Q12 — Basics of Extraction · hard · numerical
An ore contains 40 percent by mass of a metal. What mass of this ore must be processed to obtain 200 kg of the pure metal, assuming complete recovery?
A. 500 kg ✓ Correct
B. 80 kg
C. 200 kg
D. 400 kg
Solution: If 40 percent of the ore is metal, then metal mass = 0.40 times the ore mass. So the ore mass needed = 200 / 0.40 = 500 kg to obtain 200 kg of metal.