The loudness of a sound depends upon

$(a)$ Which of the following frequencies are audible to human ears: $2 \, Hz$,$5 \, Hz$,$20 \, Hz$,$200 \, Hz$,$2000 \, Hz$?
$(b)$ How are moths of certain families able to escape capture?

$A$ vibrating tuning fork is placed over the mouth of a burette filled with water. The tap is opened and the water level gradually falls. It is observed that the sound becomes the loudest for a particular length of air column.
$(i)$ What is the name of the phenomenon taking place when this happens?
$(ii)$ Why does the sound become the loudest?
$(iii)$ How does the frequency of the loud sound compare with that of the tuning fork?
$(iv)$ State the unit for measuring loudness.

The audible range for a normal human being is

If an explosion takes place at the bottom of a lake,what type of shock waves will be produced in the water?

Explain why there is usually a time delay between observing a flash and hearing a thunder?