Pakistan MCQs

Alloys combine metals with other elements.
They are designed for strength, corrosion resistance, or other useful properties.

Coal formed from buried plant matter over geological time.
Heat and pressure changed the material into carbon-rich fuel.

Brass contains mainly copper and zinc.
It is used in fittings, instruments, and decorative items.

Crude petroleum contains many hydrocarbon compounds.
Refining separates it into useful fractions.

Bronze is primarily copper alloyed with tin.
It is harder than pure copper.

Crude oil is heated and separated in a fractionating column.
Components condense at different heights according to boiling point.

Steel contains iron with a controlled amount of carbon.
Other alloying elements can modify its properties.

Petrol is a volatile petroleum fraction used in spark-ignition engines.
It contains a blend of hydrocarbons.

Chromium in stainless steel creates a thin passive oxide film.
This layer limits further corrosion.

Higher octane fuel resists premature ignition under compression.
This reduces knocking in suitable engines.

Copper conducts electricity well and can be drawn into wires.
It is also relatively resistant to corrosion.

Cooling slows metabolism of many microorganisms.
It also slows enzyme activity and spoilage reactions.