Pakistan MCQs

Complete combustion of carbon forms carbon dioxide.
Limited oxygen may instead produce carbon monoxide.

Sand particles are too large to pass through filter paper.
Water passes through as the filtrate.

Carbon monoxide competes with oxygen for hemoglobin.
This can deprive organs of oxygen without obvious warning.

Evaporation removes water as vapor.
The dissolved salt remains behind as crystals.

Carbon dioxide does not support combustion and is nonconductive.
It can displace oxygen around a fire.

Distillation boils water and then condenses the vapor.
Nonvolatile salts remain in the original container.

Rusting is an oxidation process requiring oxygen and moisture.
It weakens exposed iron over time.

Atoms are the basic chemical units of elements.
They contain protons, neutrons, and electrons.

Galvanization covers iron or steel with zinc.
The coating blocks moisture and can protect sacrificially.

Protons carry positive electric charge.
They are located in the atomic nucleus.

Paint forms a protective barrier.
This slows the electrochemical reactions that cause rust.

Electrons carry negative charge.
They occupy regions around the nucleus.