Practice Pakistan questions with answers and explanations.
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Brass contains mainly copper and zinc.
It is used in fittings, instruments, and decorative items.
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Bronze is primarily copper alloyed with tin.
It is harder than pure copper.
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Steel contains iron with a controlled amount of carbon.
Other alloying elements can modify its properties.
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Chromium in stainless steel creates a thin passive oxide film.
This layer limits further corrosion.
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Copper conducts electricity well and can be drawn into wires.
It is also relatively resistant to corrosion.
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Aluminium has a low density and good corrosion resistance.
Its alloys are widely used in aircraft.
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Mercury remains liquid at typical room temperatures.
Its toxicity has reduced its use in household instruments.
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Pencil cores are made mainly of graphite mixed with clay.
Graphite is a form of carbon.
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In graphite, each carbon forms three bonds and leaves mobile electrons.
These electrons carry charge along the layers.
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Washing soda is hydrated sodium carbonate.
It is used for cleaning and softening water.
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Diamond and graphite are allotropes of carbon.
Their different structures give very different properties.
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Bleaching powder releases chlorine-containing disinfecting agents.
It is used in water treatment and bleaching.
