Flash of lightning reaches earlier than the sound of thunder. Why?

$A$ 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.

Establish the relationship between the speed of sound, its wavelength, and frequency. If the velocity of sound in air is $340 \, m \, s^{-1}$, calculate:
$(i)$ The wavelength when the frequency is $256 \, Hz$.
$(ii)$ The frequency when the wavelength is $0.85 \, m$.

Define frequency,amplitude,and speed of a sound wave.

Write true or false for the following statement: Sound produced by a sounding body of frequency $300 \text{ Hz}$ covers $34 \text{ m}$ in the time the sounding body produces $30$ vibrations.

$(i)$ Which property of sound wave determines:
$(a)$ loudness
$(b)$ pitch?
$(ii)$ $A$ $SONAR$ station picks up a return signal after $3 \ s$. How far away is the object? (Speed of sound in water is $1440 \ m \ s^{-1}$)
$(iii)$ How can reverberations in a big hall or auditorium be reduced?