When pressure on a gaseous medium is changed at constant temperature,what will be the effect on the speed of sound wave in it?

$A$ 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:

The velocity of sound measured at a given temperature in oxygen and hydrogen is in the ratio of:

Consider the sound wave travelling in ideal gases of $He$,$CH_4$,and $CO_2$. All the gases have the same ratio $\frac{P}{\rho}$,where $P$ is the pressure and $\rho$ is the density. The ratio of the speed of sound through the gases $V_{He}: V_{CH_4}: V_{CO_2}$ is given by

$A$ metal rod of $1 \; m$ length is dropped vertically onto a hard metal floor. Using an oscilloscope,it is determined that the impact produces a longitudinal wave of $1.2 \; kHz$ frequency. The speed of sound in the metal rod is: (in $; m/s$)

An engine approaches a hill with a constant speed. When it is at a distance of $0.9 \, km$,it blows a whistle whose echo is heard by the driver after $5 \, s$. If the speed of sound in air is $330 \, m/s$,then the speed of the engine is .... $m/s$.