PMS Everyday Science MCQs

Each water molecule has two hydrogen atoms and one oxygen atom.
Its formula is H₂O.

Carbon dioxide contains one carbon atom and two oxygen atoms.
Its formula is CO₂.

An element contains atoms with the same number of protons.
It cannot be broken into simpler substances by ordinary chemical means.

Common table salt is sodium chloride.
It consists of sodium and chloride ions.

A compound contains different elements chemically bonded together.
Its properties differ from those of its constituent elements.

Most common combustion reactions require oxygen.
Removing oxygen can extinguish a fire.

Mixture components retain many of their own properties.
They can often be separated by physical methods.

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.

Electric current measures charge passing a point per unit time.
Its SI unit is the ampere.