PPSC MCQs

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.

Sunlight travels through more atmosphere near the horizon.
Much of the shorter-wavelength light is scattered away.

Sound begins with vibrating matter.
It travels through a medium as pressure variations.

Sound requires particles to transmit vibrations.
A vacuum contains too few particles for sound propagation.

Pitch rises as vibration frequency increases.
Low frequencies produce lower-pitched sounds.

Greater wave amplitude carries more energy.
It is generally perceived as a louder sound.

Both spoons may have the same temperature.
Metal removes heat from the skin more quickly, creating a colder sensation.

Heating usually increases particle motion and separation.
This commonly causes thermal expansion.

Metal structures expand in hot weather.
Gaps prevent buckling and structural damage.

Melting occurs when a solid gains enough energy to become liquid.
It happens at the melting point under fixed pressure.

Freezing removes energy from a liquid until it forms a solid.
For pure water at standard pressure, this occurs at 0°C.