Why can we not have a conversation on the surface of the Moon?

Which of the following principles is being used in $SONAR$ technology?

The temperature at which the speed of sound in air becomes double of its value at $0^oC$ is ...... $K$.

At what temperature (in $^\circ C$) will the speed of sound in air be $3$ times its value at $0^\circ C$ (in $^\circ C$)?

$A$ sound is produced by plucking a string in a musical instrument,then

On a windless day,sound emanates isotropically from a point source. Rays of the sound waves emanated from a point source placed close to the ground are shown in the figure. Consider horizontal wind towards the left blowing with constant velocity,which is uniform everywhere. In the following figures,rays of sound waves in the presence of the wind are shown. Which one is the most correct representation?