$A$ car is moving with a speed of $72 \,km/h$ towards a hill. The car blows its horn at a distance of $1800 \,m$ from the hill. If the echo is heard after $10 \,s$, the speed of sound (in $m/s$) is:

Which of the following statements is $NOT$ true?

Write the equation for the speed of a sound wave in an ideal gas.

Derive the expression for the speed of a sound wave and obtain the equations for the speed of sound in different media.

Assume that the displacement $(s)$ of air is proportional to the pressure difference $(\Delta p)$ created by a sound wave. Displacement $(s)$ further depends on the speed of sound $(v)$,density of air $(\rho)$,and the frequency $(f)$. If $\Delta p \approx 10 \, Pa$,$v \approx 300 \, m/s$,$\rho \approx 1 \, kg/m^3$,and $f \approx 1000 \, Hz$,then $s$ will be of the order of (take multiplicative constant to be $1$).

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