Which of the following frequencies of sound waves is audible to human beings?

The ratio of the velocity of sound in hydrogen gas $(\gamma = 7/5)$ to that in helium gas $(\gamma = 5/3)$ at the same temperature is

$A$ 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 $; m/s$)

What is the effect of humidity on sound waves when humidity increases?

Two sound sources produce waves at a certain temperature in air with wavelengths $50 \text{ cm}$ and $50.5 \text{ cm}$ respectively. The frequencies of the sources differ by $6 \text{ Hz}$. The velocity of sound in air at the same temperature is (in $\text{ m/s}$)

Speed of sound in air near room temperature is approximately