Sound waves travel fastest in

The speed of sound in oxygen $(O_2)$ at a certain temperature is $460 \,ms^{-1}$. The speed of sound in helium $(He)$ at the same temperature will be (assume both gases to be ideal): (in $\,ms^{-1}$)

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

Which of the following is not a transverse wave?

Sound waves of wavelength greater than that of audible sound are called

The densities of two diatomic gases at constant temperature and pressure are $d_1$ and $d_2$. The ratio of the speed of sound in these gases is: