$A$ 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:

$A$ narrow sound pulse (for example,a short pip by a whistle) is sent across a medium.
$(a)$ Does the pulse have a definite $(i)$ frequency,$(ii)$ wavelength,$(iii)$ speed of propagation?
$(b)$ If the pulse rate is $1$ after every $20 \; s$,(that is,the whistle is blown for a split of a second after every $20 \; s$),is the frequency of the note produced by the whistle equal to $1/20$ or $0.05 \; Hz$?

Two monoatomic ideal gases $A$ and $B$ of molecular masses $m_1$ and $m_2$ respectively,are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas $A$ to that in gas $B$ is given by

At what temperature will the speed of sound be nearly $1.5$ times its value at $N.T.P.$ (in $^{\circ} C$)?

For a particular sound wave propagating in air, a path difference between two points is $0.54 \, m$ which is equivalent to a phase difference of $(1.8 \pi)$. If the velocity of the sound wave in air is $330 \, m/s$, the frequency of this wave is: (in $Hz$.)

$A$ big explosion on the moon cannot be heard on the earth because