PPSC Everyday Science MCQs

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

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

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

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

Light changes speed when moving between media.
This speed change usually causes bending, called refraction.

Light from the submerged part changes direction when leaving water.
The brain traces rays backward and sees an apparent displacement.

Spectacle lenses change the convergence of light entering the eye.
They help focus images correctly on the retina.

The iris changes the size of the pupil.
This regulates how much light enters the eye.

The lens focuses incoming light onto the retina.
Photoreceptor cells then convert light into nerve signals.

Red light has the longest wavelength in the visible spectrum.
Violet has the shortest visible wavelength.

Violet light has the shortest wavelength among visible colors.
It also has the highest visible-light frequency.

Rayleigh scattering is stronger for shorter visible wavelengths.
Scattered blue light reaches observers from many directions.