FPSC MCQs

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.

Aluminium has a low density and good corrosion resistance.
Its alloys are widely used in aircraft.

High salt concentration lowers available water through osmosis.
Many spoilage microbes cannot grow well under these conditions.

Mercury remains liquid at typical room temperatures.
Its toxicity has reduced its use in household instruments.

Concentrated sugar binds water and creates high osmotic pressure.
This inhibits many microorganisms.

Pencil cores are made mainly of graphite mixed with clay.
Graphite is a form of carbon.

The reaction produces carbon dioxide gas.
Gas bubbles become trapped and expand during heating.

Washing soda is hydrated sodium carbonate.
It is used for cleaning and softening water.

Bleaching powder releases chlorine-containing disinfecting agents.
It is used in water treatment and bleaching.

Litmus changes color depending on acidity or basicity.
Red litmus turns blue in bases, while blue litmus turns red in acids.