$A$ man sets his watch by a whistle that is $2\, km$ away. How much will his watch be in error? (Speed of sound in air = $330\, m/s$)

Which one of the following statements is true?

Newton assumed that sound propagation in a gas takes place under which condition?

$A$ hospital uses an ultrasonic scanner to locate tumours in a tissue. What is the wavelength of sound in the tissue in which the speed of sound is $1.7 \; km/s$? The operating frequency of the scanner is $4.2 \; MHz$.

The pressure wave,$P = 0.01 \sin(1000t - 3x) \, N m^{-2}$,corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is $0 \, ^oC$. On some other day when temperature is $T$,the speed of sound produced by the same blade and at the same frequency is found to be $336 \, m s^{-1}$. The approximate value of $T$ is .... $^oC$

Why are the bells in temples and schools made of metal and not of wood?