The speed of sound in any gas depends upon

The enclosed air inside a closed box of rigid walls has pressure $P_1$. The density of air inside this box is constant. On heating the gas, the pressure of the enclosed air is increased from $P_1$ to $P_2$. Now it is observed that the sound travels $1.4$ times faster than at pressure $P_1$. The ratio $P_2/P_1$ is:

When an aeroplane attains a speed higher than the velocity of sound in air,a loud bang is heard. This is because

The ratio of the velocity of sound in hydrogen gas to that in oxygen gas at a given temperature is:

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

The speed of sound in oxygen $(O_2)$ at a certain temperature is $460 \, m/s$. The speed of sound in helium $(He)$ at the same temperature will be ............. $m/s$ (assume both gases to be ideal).