Pakistan MCQs

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.

Non-luminous objects become visible when illuminated.
Reflected light enters the eyes and forms an image.

Sound waves can reflect from distant surfaces.
If the delay is sufficient, the reflected sound is heard as an echo.

Reflection from a smooth surface obeys equal incidence and reflection angles.
Both angles are measured from the normal.

Soft porous materials absorb part of the sound energy.
This reduces excessive reverberation and improves clarity.

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.